Extract BLS library used in polybft to a standalone package

[Stefan-Ethernal]

Description

This PR extracts bls signing abstractions already used for polybft consensus protocol, which relies on this library https://github.com/umbracle/go-eth-bn256 to Edge standalone package.

Changes include

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)

Breaking changes

Please complete this section if any breaking changes have been made, otherwise delete it

Checklist

• I have assigned this PR to myself
• I have added at least 1 reviewer
• I have added the relevant labels
• I have updated the official documentation
• I have added sufficient documentation in code

Testing

• I have tested this code with the official test suite
• I have tested this code manually

Manual tests

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Documentation update

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Additional comments

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[igorcrevar]

Just a small remark, otherwise good

[vcastellm]

If this is not IBFT backwards compatible maybe IBFT can be removed at this point?

[Stefan-Ethernal]

If this is not IBFT backwards compatible maybe IBFT can be removed at this point?

We can discuss it and decide, I was thinking the same.

However, I'd still prefer to have this PR merged (first), because:

• I find it useful to extract the bls package to a separate one, outside of the polybft, because it should not be tied with any specific consensus protocol,
• removing IBFT entirely represents a larger effort.

Does it make sense?