VSCE: Post-release cleanup

Created by: tjkandala

Context

Due to time constraints, we did most v1 development for the VS Code extension on a large feature branch (tjk/vsce-search-ui). Subsequent bug fixes and the first few (manual) releases have been made on this branch.

Now that I've returned from a few weeks off/at low capacity, I'm working on cleaning up the mess so we can do iterative development with automated testing and releases. This is an umbrella issue to track this effort.

Work

• Rebase tjk/vsce-search-ui onto main
• Add client/vscode directory to codecov.yml ignore: (PR #32676)
  • Note: remove after adding test infrastructure
• Update developer documentation (PR #32678)
• Create PRs for tjk/vsce-search-ui changes made in packages other than client/vscode for ease of review/testing (isolate effect of changes to web app).
  • SearchSidebar: forceButton prop for search type links (PR: #32688)
  • SearchBox: setEditor prop for focus (PR: #32693)
  • Search results: onSelect prop to attach callback to file matches, etc.
    • Should include fix for #30585 (closed)
    • Note: fixed in feature branch
  • StreamingSearchResultsList props (PR: #33618)
• Once dependent PRs are merged, rebase tjk/vsce-search-ui again. Thoroughly test VS Code extension build for regressions, then merge into main
• Implement automated testing (#26453 (closed))
  • Add smoke test to ensure the extension compiles so that we have some protection while coming up with good infrastructure (good thinking @philipp-spiess!)
  • Remove client/vscode directory from codecov.yml ignore:
• Implement automated releases (#26437 (closed))
• Delete prototype branches/PRs