Hash password

Fixes issues with unexpected characters breaking things when setting the
cookie (like semicolons).

This change as-is does not affect the security of code-server
itself (we've just replaced the static password with a static hash) but
if we were to add a salt in the future it would let us invalidate keys
by rehashing with a new salt which could be handy.

src/node/util.ts

@@ -67,6 +67,10 @@ export const generatePassword = async (length: number = 24): Promise<string> =>
 	return buffer.toString("hex").substring(0, length);
 };
 
+export const hash = (str: string): string => {
+	return crypto.createHash("sha256").update(str).digest("hex");
+};
+
 export const getMediaMime = (filePath?: string): string => {
 	return filePath && (vsGetMediaMime(filePath) || (<{[index: string]: string}>{
 		".css": "text/css",