Feat: user search to fetch list of similar usernames

Feat: new user search endpoint to fetch list of similar usernames

Description

This MR is for a new /users/search which returns a list of usernames which are the most similar to the search query

Checklist

• Code has been refactored for clarity, maintainability, or performance.
• No functional changes have been introduced.
• All existing tests are passing.
• Code adheres to project coding standards.

Related Issue(s)

Closes #