Fix broken usings in regenerated Suite EF Core repositories #23009
BackVolosoftWorkspace#1757
PrependUsingsIfAbsent split an incomplete using X.%%dbcontext-namespace%%; into two broken lines when RepositoryCommand added navigation usings. It now only inserts the new usings there, after #defines, extern aliases and global usings.
Also fixes the other errors found while regenerating real solutions (backend/UI only generation, Excel/tests/navigation toggles, child entity delete, Angular bulk delete, MongoDB/microservice/module cases).