Implement Shutter on Gnosis Chain

[rubo]

Changes

• Block production for Shutter transactions
• Fetching logs from events
• Receiving decryption keys from Keyper p2p network
• Get eon information from contracts
• Check validator registration

Types of changes

What types of changes does your code introduce?

• [ ] Bugfix (a non-breaking change that fixes an issue)
• [x] New feature (a non-breaking change that adds functionality)
• [ ] Breaking change (a change that causes existing functionality not to work as expected)
• [ ] Optimization
• [x] Refactoring
• [ ] Documentation update
• [ ] Build-related changes
• [ ] Other: Description

Todo

• [x] Refactor as Shutter plugin instead of AuRa #7307
• [x] Retrieve logs on new block and store #7310
• [x] Shutter block improvement
• [ ] Improve unit tests, add E2E test
• [ ] Add metrics
• [ ] (LibP2P) Implement basic peer discovery
• [ ] (LibP2P) Investigate ARM connection issues
• [ ] (LibP2P) Should not need EnablePreviewFeatures
• [ ] (bls-bindings) Audit bindings code

Testing

Requires testing

• [x] Yes
• [ ] No

If yes, did you write tests?

• [x] Yes
• [ ] No

Documentation

Requires documentation update

• [x] Yes
• [ ] No

Requires explanation in Release Notes

• [x] Yes
• [ ] No

[Marchhill]

SequencerContract cannot search through all blocks all the time.

Overall too much LINQ, multiple enumerations in many places. Please make private things private.

There were quite a few places I used internal and InternalsVisibleTo with the intention of adding unit tests for them - do you think I should remove this and do it some other way?