* Implement basic scheme CRUD endpoints.
* Get All Schemes (Paged) Endpoint and store plumbing.
* Add get teams/channels for schemes.
* Fix unit tests.
* Review fixes.
* More review fixes.
* Add Scheme model and stub store.
* Port ChannelStore to be Scheme aware.
* Make almost all the API/APP layer work with ChannelSchemes.
Only thing still hacky is UpdateChannelMemberRoles().
* Add basic SchemeStore implementation.
* Migrate UpdateChannelMemberRoles properly and fix tests.
* Update store tests and mocks so they work.
* Include creating default roles in Scheme create store function.
* Implement role deletion and start scheme deletion.
* Only use non-deleted roles for authorization.
* Add GetByScheme method to Team store.
* Add GetChannelsByScheme.
* Update store mocks.
* Implement scheme deletion in the store.
* Rename is valid function.
* Add offset and limit to queries to fetch teams and channels by scheme.
* Fix queries.
* Implement scheme awareness in Team store and add a migration.
* Tidy up ChannelStore mapping functions and add exhaustive unit tests.
* Add all missing i18n.
* Proper tests for TeamStore internal functions and fix them.
* Make additional TeamMember fields nullable.
* Make new ChannelMember fields nullable.
* Create new nullable columns without defaults.
* Make new fields in large tables nullalble.
* Fix empty list of TeamMembers.
* Deduplicate SQL queries.
* Fix spelling.
* Fix review comment.
* More review fixes.
* More review fixes.
* fix in:channel search when channel name/displayname includes `-`
* fix failing test in PostgreSQL
* add lowercase indexes of channel's name and displayname to postgresql, and add unit tests
