[BC] Allow only `bool` tensors as mask in `masked_select` (#96112)
`byte` support was marked as deprecated in 1.8, so it's fine to remove this in 2.1 (or even 2.0)
Deprecation warning was added by https://github.com/pytorch/pytorch/pull/22261
Also, fix bunch of syntactic errors in comments
Pull Request resolved: https://github.com/pytorch/pytorch/pull/96112
Approved by: https://github.com/ezyang
