24144 Add focus state to todo button on sidebar

What does this MR do?

Adds darker focus state to todo button on sidebar

Are there points in the code the reviewer needs to double check?

If there are any other buttons that don't have a darker background on focus

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #24144 (closed)