fix(NOTIFY-1166): only fire callback when account name has changed

[mathieuartu]

Explanation

This PR ensures the onAccountNameUpdated callback only fires when the new name is different from the previous one

References

NOTIFY-1166

Changelog

@metamask/profile-sync-controller

• FIXED: onAccountNameUpdated will now fire only when the new name is different from the previous one

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've highlighted breaking changes using the "BREAKING" category above as appropriate
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes