Check if user is in room before being able to tag it

[lamoboos223]

Create a function in room_member handler to check if a user is a member of a room

Check if a user is in a room before tagging it

Fix #17819

Pull Request Checklist

• Pull request is based on the develop branch
• Pull request includes a changelog file. The entry should:
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• Code style is correct
  (run the linters)

[CLAassistant]

All committers have signed the CLA.

[lamoboos223]

Closes #17819

[MadLittleMods]

Looking good!

Just a few formatting things

[MadLittleMods]

Thanks for the contribution @lamoboos223 🦝

[lamoboos223]

My pleasure, Eric 🤝

@MadLittleMods