HTTP proxy

Otherwise the request will just hang.

Also fixed a type issue.

The raw value is now passed back to VS Code so it can do the parsing
with its own URI class rather than trying to parse using Node's url
module first since that has no guarantee of working the same way. It
also lets us keep the vscode-remote bit internal to VS Code.

Removed the logic that keeps trying paths until it finds a valid one
because it seems confusing to open a path and silently get some other
path instead of an error for the one you tried to open. Now it'll just
use exactly what you specified or fail trying.

Fixes #1488. The problem here was that url.parse was encoding the spaces
then the validation failed looking for a literal %20.

Send report issues to code-server repo

Back up old directory when updating

This makes the code much more internally consistent (providers just
return payloads, include the proxy provider).

There's no need to specially construct the path.

Otherwise they'll crash code-server.

This simplifies the logic a bit.

The cookie will be set for the proxy domain so it'll work for all of its
subdomains.

It'll be able to handle /proxy requests as well as subdomains.

This allows it to be used in subdomains.

This will be used for proxying ports.

- Add type to HTTP options.
- Fix certificate message always saying it was generated.
- Dedent output not directly related to the HTTP server.
- Remove unnecessary comma.

In Google cloud shell the host header is 127.0.0.1:8080 instead of the
actual URL. This is what we write out to the HTML so VS Code can pick it
up. However cloud shell rewrites this string when found in the HTML
before serving it so it becomes https://8080-[...].appspot.com,
resulting in an extra unexpected https:// in the
URI (vscode-remote://https://8080[...]). The resulting malformed URI
causes the extension host to exit.

- Fixes #1471
- Fixes #1468
- Fixes #1440 (most likely).

That way if they happen to conflict code-server doesn't crash.

Peg yarn version to ensure deterministic builds

"Yarn is fully deterministic as long as all your teammates are using the same Yarn version." (https://classic.yarnpkg.com/blog/2017/05/31/determinism/)

They aren't used so we can skip them.