Quantization: Enable 2-bit in QuantModules

[jambayk]

Describe your changes

• Update the supported bits to [2, 4, 8]

Checklist before requesting a review

• Add unit tests for this change.
• Make sure all tests can pass.
• Update documents if necessary.
• Lint and apply fixes to your code by running lintrunner -a
• Is this a user-facing change? If yes, give a description of this change to be included in the release notes.

(Optional) Issue link