[BE] Deprecate `has_XYZ` attributes (#103279)
Use [`__getattr__`](https://peps.python.org/pep-0562/) to raise warningwhen one tries to access `has_XYZ` methods and recommend appropriate `torch.backends.XYZ` methods
Make respective properties in `torch._C` private (by prefixing them with underscore), to exclude from `from torch._C import *`.
Added `warnings.simplefilter` to workaround Python-3.11 torch.compile lineinfo issue.
Fixes https://github.com/pytorch/pytorch/issues/102484
Pull Request resolved: https://github.com/pytorch/pytorch/pull/103279
Approved by: https://github.com/janeyx99, https://github.com/Skylion007
