• Fix the callback URI
• This needs to match the URI in the oauth app
• Fix manual token entry
  • Currently it just errors with "network error"
• Fix final redirect
  • I believe it'll redirect to code-oss://something but it's currently not doing that, maybe because it doesn't match the callback URI (which is using vscode://).
  • We'll need to register a handler for the code-oss scheme (https://developer.mozilla.org/en-US/docs/Web/API/Navigator/registerProtocolHandler/Web-based_protocol_handlers). However it must start with web+, so let's use web+code-server.
• Might need to create our own oauth application to get this working due to VS Code using a scheme we can't use (vscode://).

Closes #1883
Closes #2253