Add resource allocation schema for Mattermost team creation

• Mattermost requires a team url, team name as well as an invite-only flag to create a new team on behalf of an authenticated user.
• MmTeamResourceSpecV1 defines these team attributes and MmTeamResourceAllocateV1 defines the allocation of the resource.
• ResourceCreatedV1 can be reused for the response and ErrorV1 for any failed requests.

Relates to #3 (closed)