Group creation requests API

[eguerrant]

Still need to iterate and debug and fix tests and all that jazz

Not ready for review

Description

This PR introduces the concept of 'Group Creation Requests', sometimes referred to in the code as Group Requests. This will allow users to, as the name suggests, request that a group is created.

The user provides the desired group:

• Name
• Description
• Tags
• Ownership Duration
• Group type
• (if an App Group) Associated app
• Request reason (this will also be used as the ownership reason for the initial owner)

This request is then created so that Access admins (and app owners if the requested group is an app group) can approve/reject it. Users may also reject their own requests.

• If an app owner requests that a group is added to their own app, it will automatically be approved
• If the requested or approved ownership duration is longer than tag constraints allow, it will automatically be lowered to the maximum allowed value. In the case of app groups, app tags will also be applied.
• The requesting user will automatically be added as the owner of the group. (This may be changed in the future to allow requesters to specify an owner)
• The approving user may modify the group name, description, tags, app, group type, and ownership duration before approving

Additional changes have been added to the plugins and audit logging to support the new request type

Notes

A few other bug fixes and circular import fixes added in as well (eg. in modify_group_tags.py)

How to review

Unfortunately, this PR is massive and not easily broken up. Probably start with models and schemas in case any changes need to be made there (which will affect the rest of the code), then operations, then the rest

TODO after initial review

• Database migrations (I'd like to avoid having to re-do them if I have to change the model after review)

TODO in follow up PRs:

• Notifications update
• UI update