Adding gpu training support for chemberta and grover

[arunppsg]

Description

To train models on gpu, we need to move the tensors to the gpu device.
In the earlier implementation, this piece was missing (credits to myself).
I have added the missing piece here - moving of tensors to gpu for training models on gpu.

Along with this, I have added support mps backend for training on apple m1 gpu.

Corresponding changes have been made to tests to pin the device as cpu during testing.

Type of change

Please check the option that is related to your PR.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • In this case, we recommend to discuss your modification on GitHub issues before creating the PR
• Documentations (modification for documents)

Checklist

• My code follows the style guidelines of this
  project
  • Run yapf -i <modified file> and check no errors (yapf version must be 0.32.0)
  • Run mypy -p deepchem and check no errors
  • Run flake8 <modified file> --count and check no errors
  • Run python -m doctest <modified file> and check no errors
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New unit tests pass locally with my changes
• I have checked my code and corrected any misspellings

[rbharath]

LGTM

Feel free to merge when ready