Autocomplete: add git metadata to autocomplete requests

[valerybugakov]

• WIP
• Adds PCW metadata to autocomplete requests for enterprise users:

  metadata?: {
      /**
       * File path relative to the git root.
       */
      gitFilePath?: string
      /**
       * Repository names resolved using Sourcegraph API based on remote URLs (such as `github.com/foo/bar`).
       */
      gitRepoNames?: string[]
      /**
       * git rev-parse HEAD
       */
      gitCommitHash?: string
  }

• TODO:
  • Manual testing
  • New unit tests
  • Add gitCommitHash. Getting an always green commit hash will be tricky for autocomplete in the agent where we don't have the Git VS Code extension. We don't want to touch fs on every request, and we don't have any file-watching infra setup to get notifications about .git/HEAD being updated. I plan to add a naive timeout-based caching to start with.
• Part of https://linear.app/sourcegraph/issue/CODY-4122/ide-clients-include-repository-name-and-git-file-path-in-chat

Test plan

CI

Changelog

• Adds

[olafurpg]

Make this an array? I can imagine we'll support multi-file edits at one point, and the request will be associated to multiple files.

[olafurpg]

I'm guessing that these repo names will be using sourcegraph formatting like github.com/sourcegraph/name?

[valerybugakov]

Yes, we use Sourcegraph API to resolve repo names based on remote URLs.

[olafurpg]

Thank you for this! How big of a pull would it be to additionally capture this metadata for chat requests (including edit and smart apply)?

As a starting point, we're going to focus on chat for the audit log because the autocomplete request volume is ~30-50x larger and quite a bit noisier. Almost all CLI/API clients hit chat only.

This PR LGTM 👍🏻 I mostly reviewed the metadata format, and didn't thoroughly review the diffs that propagate the information correctly.