Fix selection colors

[madebyisaacr]

Description

This pull request fixes and improves text selection colors across various plugins.

• Text Search: added tint-colored text selection color (it was missing due to not using the default plugin CSS)

Before	After

• Notion & Google Sheets: made text selection bg color match custom tint color.
• Ashby, Recruitee, PR.co: these plugins have a dark tint color, so I made the text selection colors white in dark theme to fix low contrast.

Before	After

• Greenhouse: made custom tint color apply in both light and dark themes, and changed tint color to a lighter green color for proper contrast in both themes (from Greenhouse's brand page)

Before	After

Changelog

• Improved text selection colors.

Testing

• Verify new text selection colors