CodeQL model editor: Don't highlight row when clicking inside text box

[shati-patel]

When you click the Type input boxes in the model editor (for Ruby), this shouldn't select/deselect the row:

(Inspired by c8d3127, which disables (de)selection when you click a dropdown)

Checklist

N/A: Feature-flagged for internal use for now.

• 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]

Seems sensible to me