Allow Mattermost team creation when enabling Mattermost Command
When using Omnibus installation with Mattermost, we are going to have a flow to automatically add the Slash Integration to Mattermost (#24769 (closed)). While this flow shortens the time from configuration to usage, we should also cover the case when there are no teams or when the user has to create a new team. This will speed up the idea-to-production workflow setup even more.
During the installation flow of the slash commands service for Omnibus-Mattermost, let users pick an existing team or create a new team. Mattermost may restrict who can create teams, so we need to handle the error case.
Specific details of the different scenarios are noted in the design specs:
For users that can create Mattermost teams (Mattermost system admins or regular users if they have permission)
|One or more teams already available||No teams available|
|1) Select or create team 2) New team|
For users that can't create Mattermost teams
|One team available||Two or more teams available|
For users that can't create Mattermost teams nor manage integrations: display the “no permission” screen developed in #24769 (closed)
The Command trigger word field is pre-filled with the project slug. When creating teams, the team Name and URL fields are pre-filled with the group name and group slug, respectively. The users can naturally change those fields, but we take the lead and fill those for them.