Join test parterns in channnel

As any logged-in user (except. Accounting, Project Manager, User Role), when a test run is started,
then Gazelle TM shall invite me/add me to the private channel (only if I belong in the same Test session).

To be verified: A user from another Test session MUST not be allowed neither to join a TR nor to join the TR channel from another Test Session.

Note: a new testing-session role with a qualifier of an active Testing session such as EUCAT could be used within the Keycloack CAS to control this.

Acceptance criteria:

ask to join channel => accepted
 refuse to join channel => denied

As SUT operator ,when a hit the "join" button on chat room( Gazelle TM),
then i'm automatically added to the channel.

 Acceptance criteria:
- click "join" button => display on chat room,link to the channel
- "join" button for allow SUT operator