Serve webviews from the same origin

Normally webviews are served from vscode-webview.net but we would rather them be
self-hosted.

When doing this CSP will block resources (for example when viewing images) so
add 'self' to the CSP to fix that.

Additionally the service worker defaults to handling *all* requests made to the
current host but when self-hosting the webview this will end up including the
webview HTML itself which means these requests will fail since the communication
channel between the webview and the main thread has not been set up yet as the
webview itself is not ready yet (it has no HTML and therefore no script either).
Since this code exists only for the authentication case we can just skip it when
it is served from the current host as authentication is not a problem if the
request is not cross-origin.

There is also an origin check we bypass (this seems to be related to how the
webview host is separate by default but we serve on the same host).

To test, open a few types of webviews (images, markdown, extension details, etc).

Make sure to update the hash. To do so:
1. run code-server 
2. open any webview (i.e. preview Markdown)
3. see error in console and copy hash

That will test the hash change in pre/index.html

Double-check the console to make sure there are no console errors for the webWorkerExtensionHostIframe
which also requires a hash change.

parentOriginHash changes

This fixes webviews from not working properly due to a change upstream.
Upstream added a check to ensure parent authority is encoded into the webview
origin. Since our webview origin is the parent authority, we can bypass this
check.

Index: code-server/lib/vscode/src/vs/workbench/services/environment/browser/environmentService.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/workbench/services/environment/browser/environmentService.ts
+++ code-server/lib/vscode/src/vs/workbench/services/environment/browser/environmentService.ts
@@ -225,7 +225,7 @@ export class BrowserWorkbenchEnvironment
 
 	@memoize
 	get webviewExternalEndpoint(): string {
-		const endpoint = this.options.webviewEndpoint
+		const endpoint = (this.options.webviewEndpoint && new URL(this.options.webviewEndpoint, window.location.toString()).toString())
 			|| this.productService.webviewContentExternalBaseUrlTemplate
 			|| 'https://{{uuid}}.vscode-cdn.net/{{quality}}/{{commit}}/out/vs/workbench/contrib/webview/browser/pre/';
 
Index: code-server/lib/vscode/src/vs/server/node/webClientServer.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/server/node/webClientServer.ts
+++ code-server/lib/vscode/src/vs/server/node/webClientServer.ts
@@ -323,6 +323,7 @@ export class WebClientServer {
 
 		const workbenchWebConfiguration = {
 			remoteAuthority,
+			webviewEndpoint: vscodeBase + this._staticRoute + '/out/vs/workbench/contrib/webview/browser/pre',
 			_wrapWebWorkerExtHostInIframe,
 			developmentOptions: { enableSmokeTestDriver: this._environmentService.args['enable-smoke-test-driver'] ? true : undefined, logLevel: this._logService.getLevel() },
 			settingsSyncOptions: !this._environmentService.isBuilt && this._environmentService.args['enable-sync'] ? { enabled: true } : undefined,
Index: code-server/lib/vscode/src/vs/workbench/contrib/webview/browser/pre/index.html
===================================================================
--- code-server.orig/lib/vscode/src/vs/workbench/contrib/webview/browser/pre/index.html
+++ code-server/lib/vscode/src/vs/workbench/contrib/webview/browser/pre/index.html
@@ -5,7 +5,7 @@
 	<meta charset="UTF-8">
 
 	<meta http-equiv="Content-Security-Policy"
-		content="default-src 'none'; script-src 'sha256-QA1gXilHYAUFCvp7MpjgcmyBCFzSKV0SpiecMU8aUVc=' 'self'; frame-src 'self'; style-src 'unsafe-inline';">
+		content="default-src 'none'; script-src 'sha256-5X5RiKYn8NTJVx919WStPrAmsV80rIIBbePhKquPcAQ=' 'self'; frame-src 'self'; style-src 'unsafe-inline';">
 
 	<!-- Disable pinch zooming -->
 	<meta name="viewport"
@@ -335,6 +335,12 @@
 
 				const hostname = location.hostname;
 
+				// It is safe to run if we are on the same host.
+				const parent = new URL(parentOrigin)
+				if (parent.hostname === hostname) {
+					return start(parentOrigin)
+				}
+
 				if (!crypto.subtle) {
 					// cannot validate, not running in a secure context
 					throw new Error(`'crypto.subtle' is not available so webviews will not work. This is likely because the editor is not running in a secure context (https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts).`);
Index: code-server/lib/vscode/src/vs/workbench/contrib/webview/browser/pre/index-no-csp.html
===================================================================
--- code-server.orig/lib/vscode/src/vs/workbench/contrib/webview/browser/pre/index-no-csp.html
+++ code-server/lib/vscode/src/vs/workbench/contrib/webview/browser/pre/index-no-csp.html
@@ -334,6 +334,12 @@
 
 				const hostname = location.hostname;
 
+				// It is safe to run if we are on the same host.
+				const parent = new URL(parentOrigin)
+				if (parent.hostname === hostname) {
+					return start(parentOrigin)
+				}
+
 				if (!crypto.subtle) {
 					// cannot validate, not running in a secure context
 					throw new Error(`'crypto.subtle' is not available so webviews will not work. This is likely because the editor is not running in a secure context (https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts).`);
Index: code-server/lib/vscode/src/vs/workbench/services/extensions/worker/webWorkerExtensionHostIframe.html
===================================================================
--- code-server.orig/lib/vscode/src/vs/workbench/services/extensions/worker/webWorkerExtensionHostIframe.html
+++ code-server/lib/vscode/src/vs/workbench/services/extensions/worker/webWorkerExtensionHostIframe.html
@@ -4,7 +4,7 @@
 		<meta http-equiv="Content-Security-Policy" content="
 			default-src 'none';
 			child-src 'self' data: blob:;
-			script-src 'self' 'unsafe-eval' 'sha256-/r7rqQ+yrxt57sxLuQ6AMYcy/lUpvAIzHjIJt/OeLWU=' https:;
+			script-src 'self' 'unsafe-eval' 'sha256-TkIM/TmudlFEe0ZRp0ptvN54LClwk30Rql4ZPE0hm/I=' https:;
 			connect-src 'self' https: wss: http://localhost:* http://127.0.0.1:* ws://localhost:* ws://127.0.0.1:*;"/>
 	</head>
 	<body>
@@ -23,6 +23,13 @@
 			// validation not requested
 			return start();
 		}
+
+		// It is safe to run if we are on the same host.
+		const parent = new URL(parentOrigin)
+		if (parent.hostname === hostname) {
+			return start()
+		}
+
 		if (!crypto.subtle) {
 			// cannot validate, not running in a secure context
 			return sendError(new Error(`Cannot validate in current context!`));