cross platform from_pretrained (#20538)
* add support for `from_pt`
* add tf_flax utility file
* Update src/transformers/modeling_tf_flax_utils.py
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
* remove flax related modifications
* add test
* remove FLAX related commits
* fixup
* remove safetensor todos
* revert deletion
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>