Updates design of unresolved discussions counter

What does this MR do and why?

• Updates the design of the unresolved discussions counter.
• If the project has the setting for all threads must be resolved turned on the background is orange, otherwise the background is gray.
• Ability to go to previous thread (instead of just next)

Screenshots or screen recordings

All threads must be resolved	Threads don't need to be resolved

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Closes #360569 (closed)

#356703 (closed)