[FIX] Member list update when adding user

[Rishab87]

Proposed changes

I have fixed the issue of new member not showing when added to the channel immediately on UI by adding a useEfffect hook to fetch users on focus.

Issue(s)

Fixes #4644

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules