Allow [^username] to send notification to user even if the input user doesn't have browse user permission.

Summary

User mentions don't send notification if performed by a user without Browse Users permission

Steps to Reproduce

1. Login to JIRA with an account without 'Browse User ' permissions
2. Mention another users using the wiki markup [~user]

Expected Results

The mentioned user is linked if the username matches a JIRA username, and notifications are sent out of JIRA

Actual Results

The mentioned user is linked if the username matches a JIRA username, but no notifications are sent out of JIRA

Notes

In a few other contexts in JIRA it doesn't appear that the browse users permission is related to being able to trigger notifications. For instance if a user without browse users permissions updates reporter by specifying the username exactly, notifications will be sent.

Workaround

No known workaround