/Teams api enhancements, Creation of team in Github

[olivercodes]

Description:

As an evolution of the creation of teams, we would like to enhance the teams API to include features that simplify the management of team memberships and usage.

Image credit @tomclement

Features:

• If the GH team exists just associate it in the Teams API record
• If the GH team doesn't exist, just fail
• The person creating the team is allowed to do so

Requirements:

• The implementation of the above features should be done in Github, however the logic included above is abstracted away from the implementation. Similar to how we abstract datastores away from the API (the service and repository layers do not care which datastore is being used under the hood), we would expect someone to be able to implement the teams API with Azure AD or another identity system with relative ease, by implementing the teams api.
• This will require modifications to the current Teams model, as it now includes the addition of a maintainer (which is a user)
• Note: it is assumed that the maintainer will proceed to add additional members to the team via the Github Teams interface. This is an advantage to our implementation here, as it greatly reduces the overall complexity of the API, and removes the need to manage individual memberships. Changing of Maintainer (in the event of exiting the company) becomes a (rare) Platform Team operation when needed