[1.8.x] Fixed #24225, #24264, #24282 -- Rewrote model reloading in migration project state

Instead of naively reloading only directly related models (FK, O2O, M2M
relationship) the project state needs to reload their relations as well
as the model changes as well. Furthermore inheriting models (and super
models) need to be reloaded in order to keep inherited fields in sync.

To prevent endless recursive calls an iterative approach is taken.

Backport of b29f3b51 from master