Removing prototype related things from release/0.14 branch (#6687)

* Remove test related to prototype

* Remove torchvision/prototype dir

* Remove references/depth/stereo because it depend on prototype

* Remove prototype related entries on mypy.ini

* Remove things related to prototype in pytest.ini

* clean setup.py from prototype

* Clean CI from prototype

* Remove unused expect file

torchvision/prototype/datasets/utils/__init__.py

-from . import _internal  # usort: skip
-from ._dataset import Dataset
-from ._resource import GDriveResource, HttpResource, KaggleDownloadResource, ManualDownloadResource, OnlineResource

torchvision/prototype/models/__init__.py

-from . import depth

torchvision/prototype/models/depth/__init__.py

-from . import stereo

torchvision/prototype/models/depth/stereo/__init__.py

-from .raft_stereo import *
-from .crestereo import *