Variant analysis: Always read BQRS results file if it's available

[shati-patel]

Once github/codeql-variant-analysis-action#854 is merged, a succesful variant analysis run will always have the result.bqrs file available.

Instead of choosing to read interpreted results or raw results, we should support having both. (This is so that users will be able to toggle between raw and interpreted results in the results view.)

Checklist

N/A—no user impact yet 🦁

• 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.

[charisk]

Looks good!