Resolve remote authority to initialize tunnel API

[kylecarbs]

This enables the vscode.workspace.registerRemoteAuthorityResolver API to be executed.

It's specifically scoped to the "coder-link" scheme at the moment to reduce external dependency on forking VS Code functionality.

The remote host doesn't resolve to an extension host like the API expects, but instead we only utilize the tunnel functionality.

[github-actions]

✨ Coder.com for PR #4105 deployed! It will be updated on every commit.

• Host: https://codercom-720h90dww-codercom.vercel.app/docs/code-server
• Last deploy status: success
• Commit: c7a5263
• Workflow status: https://github.com/cdr/code-server/actions/runs/1214177762

[codecov]

Codecov Report

Merging #4105 (476b9c5) into main (67b23aa) will not change coverage.
The diff coverage is n/a.

❗ Current head 476b9c5 differs from pull request most recent head c7a5263. Consider uploading reports for the commit c7a5263 to get more accurate results

@@           Coverage Diff           @@
##             main    #4105   +/-   ##
=======================================
  Coverage   64.12%   64.12%           
=======================================
  Files          36       36           
  Lines        1873     1873           
  Branches      379      379           
=======================================
  Hits         1201     1201           
  Misses        571      571           
  Partials      101      101           

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[jsjoeio]

Tests are passing and I don't see how this would break anything.

Nice comments too 🚀