Remove two more internal-only commands

[robertbrignull]

Removes the codeQL.cancelVariantAnalysis and codeQL.openVariantAnalysisQueryText commands. I've done these two together in one PR since they both also use the approach from #2179.

Check the individual commits for changes relevant to each command. For each one we essentially inline the implementation so we call the method on the variant analysis manager directly instead of going through a command. The only case where we're not already inside a command is when triggered from the variant analysis view, so we add dedicated telemetry to cover that.

Checklist

• CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• Issues have been created for any UI or other user-facing changes made by this pull request.
• [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.

[koesie10]

LGTM