fix(cli): multiselect visibility for light themes

[vineetjohn]

Small QoL change to improve visibility when toggling options in a cliclack multi-select. This visibility problem only seems to exist for light themes, where there's no visible difference in text colour contrast between the cursor item and the result. Apply the same change to the 'Remove extension' and 'Experiments' dialogs as well

Multi-select prompt interaction videos

• Existing (no idea which position the cursor is at)

https://github.com/user-attachments/assets/c0ecd88d-a999-4403-b3f8-4e8f6070d2ad

• New

https://github.com/user-attachments/assets/1531d42b-c950-46b7-8030-2d7c599d31f0

[vineetjohn]

Open to other suggestions on how to improve this.

I realize this overloads what the hint argument is used for as a per-item attribute. https://docs.rs/cliclack/latest/cliclack/struct.MultiSelect.html#method.item

However, any subsequent 'correct' use of the hint will also fix the same problem.