Move selection-commands.ts to be in the vscode directory

[robertbrignull]

Should fix https://github.com/github/vscode-codeql/security/code-scanning/521

The VS Code dependency we have is on showAndLogErrorMessage and I can't see a way to remove it without reducing functionality. But we can move it to the vscode directory and I don't think this is a huge problem compared to it being just in the common directory. The places where we'll want to use these methods from are going to already have VS Code dependencies.

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.

[shati-patel]

🚢