CHIA-595: Keccak256 soft-fork

[arvidn]

This is a stripped-down version of https://github.com/Chia-Network/clvm_rs/pull/403 just implementing the keccak operator. (i.e. not the base64 operators).

The main difference is that in this PR, the keccak256 operator has opcode 62 (not 64)

[coveralls-official[bot]]

Pull Request Test Coverage Report for Build 9209975097

Details

• 24 of 24 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.04%) to 94.183%

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Totals
Change from base Build 9133482646:	0.04%
Covered Lines:	5829
Relevant Lines:	6189

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💛 - Coveralls

[arvidn]

cancelled