gh-127977: Add Base2 encoding methods (Base2MSBF and Base2LSBF) to the Base64 module

[FajarKim]

This PR adds two new encoding methods, Base2MSBF (Most Significant Bit First) and Base2LSBF (Least Significant Bit First), to the Base64 module.

Key Features

• Base2MSBF: Encodes data with the most significant bit first.
• Base2LSBF: Encodes data with the least significant bit first.
• Corresponding decoding methods are implemented to revert encoded strings back to their original byte format.

• Issue: Add Base2 encoding methods (Base2MSBF and Base2LSBF) to the Base64 module #127977

[ghost]

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[bedevere-app]

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[picnixz]

Please, before opening a PR, wait for the issue to be accepted as is. I decided that such feature should be first discussed on discourse and that it should not be in base64 as the latter is for RFC 4648. In addition, please read the https://devguide.python.org/ before opening a PR. There are mandatory steps and instructions to follow.