[edit controller] Fix composite entity reparenting when inlined This implies handling the reparenting case sooner, otherwise the child entity modifications are cancelled (see 113e9da47afc). Add a new test to ensure non-regression in all previous tests. Closes #10291977.

[forms] Do not raise errors on composite required relation being deleted The entity included in the composite will be deleted in such a case, so the field is not required even when the cardinality is '1' or '+'. Related to #8529868