[lib][native][web] Move validChatNameRegex to validation-utils.js

Summary:
This diff resolves the ReferenceError issue on web, which was occurring after the introduction of D8834.

Depends on D8945.

Test Plan:
Check if all files import validChatNameRegex, validChatNameRegexString, chatNameMaxLength from validation-utils.js

Reviewers: tomek, inka, rohan

Reviewed By: rohan

Subscribers: rohan, ashoat, tomek

Differential Revision: https://phab.comm.dev/D9061