Add a Search Within token to issues list search

What does this MR do and why?

Implements search in issue titles only (#25046 - closed)

A follow-up of Draft: Add Title filter to Issues search (!86999 - closed) and Draft: Add title and description filter to issu... (!105749 - closed)

This change adds a new Search Within token to the issues list search. With two options supported: Titles and Descriptions.

This would allow to search only by titles or descriptions in the issues list.

Screenshots or screen recordings

Screen_Recording_2022-12-05_at_15.13.16

Token list dropdown

Available options

How to set up and validate locally

1. Open project issues list
2. Enter search query
3. Select a Search Within token
4. Select either a Titles or Descriptions option
5. Hit Enter

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.