Merge branch 'share-project-ce' into 'master'

Bring from EE: Share Project with Group

- [x] Models and migrations
- [x] Logic, UI
- [x] Tests
- [x] Documentation
- [x] Share with group lock
- [x] Api feature
- [x] Api docs
- [x] Api tests

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

For #12831 

cc @DouweM @rspeicher @vsizov

See merge request !3186