Move some targets from //: to //src/core: (grpc#31402)

* temp

* temp

* temp

* top BUILD builds

* everything builds

* buildify

* temp fix_build_deps change

* fix gpr_atm

* additional changes

* fix build files

* nofixdeps

* Generate projects

* json_args

* fix context

* Generate projects

* Sprinkle some avoid_dep tags

* Run fix_build_deps

* Remove additional avoid_dep

* Revert some targets

* grpc_mock_cel