Add /absproxy to remove --proxy-path-passthrough

See https://github.com/cdr/code-server/issues/2222#issuecomment-765235938

Makes way more sense.

src/node/cli.ts

@@ -50,7 +50,6 @@ export interface Args extends VsArgs {
   "show-versions"?: boolean
   "uninstall-extension"?: string[]
   "proxy-domain"?: string[]
-  "proxy-path-passthrough"?: boolean
   locale?: string
   _: string[]
   "reuse-window"?: boolean
@@ -173,10 +172,6 @@ const options: Options<Required<Args>> = {
   "uninstall-extension": { type: "string[]", description: "Uninstall a VS Code extension by id." },
   "show-versions": { type: "boolean", description: "Show VS Code extension versions." },
   "proxy-domain": { type: "string[]", description: "Domain used for proxying ports." },
-  "proxy-path-passthrough": {
-    type: "boolean",
-    description: "Whether the path proxy should leave the /proxy/<port> in the request path when proxying.",
-  },
   "ignore-last-opened": {
     type: "boolean",
     short: "e",