Relay validator check

[bernatfp]

Adding a new action to check whether our validators (based on a specified NO ID in the configuration file) are registered with all the mev-boost relays which are whitelisted by Lido.

This PR resolves #20 which also includes more details about the approach taken.

If our validators are registered with all relays we will see something like this:

python -m swarm relay-check
Checking relay coverage for validators...
Found 9 whitelisted relays
Fetching all keys registered in CSM 120...
Found 12 validators in CSM

Relay coverage report:
--------------------------------------------------

Validator 0x8d33498678...
Registered with 9/9 relays (100.0%)

Validator 0x994d0a1177...
Registered with 9/9 relays (100.0%)

Validator 0x963367024d...
Registered with 9/9 relays (100.0%)

Validator 0x8c661e00fc...
Registered with 9/9 relays (100.0%)

...

If our validator is not registered with any relay we will see something like this:

python -m swarm relay-check
Checking relay coverage for validators...
Found 9 whitelisted relays
Fetching all keys registered in CSM 120...
Found 12 validators in CSM

Relay coverage report:
--------------------------------------------------

Validator 0x8d33498678...
Registered with 0/9 relays (0.0%)
Missing registrations for relays:
  - ('https://0x8c4ed5e24fe5c6ae21018437bde147693f68cda427cd1122cf20819c30eda7ed74f72dece09bb313f2a1855595ab677d@global.titanrelay.xyz', 'Gattaca', False, 'Titan Relay Global (non-filtering)')
  - ('https://0x8c4ed5e24fe5c6ae21018437bde147693f68cda427cd1122cf20819c30eda7ed74f72dece09bb313f2a1855595ab677d@regional.titanrelay.xyz', 'Gattaca', False, 'Titan Relay Regional (filtering)')
  - ('https://0xa7ab7a996c8584251c8f925da3170bdfd6ebc75d50f5ddc4050a6fdc77f2a3b5fce2cc750d0865e05d7228af97d69561@agnostic-relay.net', 'Agnostic', True, 'Agnostic Relay')
  - ('https://0x98650451ba02064f7b000f5768cf0cf4d4e492317d82871bdc87ef841a0743f69f0f1eea11168503240ac35d101c9135@mainnet-relay.securerpc.com/', 'Manifold Finance', False, 'Manifold SecureRPC Relay')
  - ('https://0xa1559ace749633b997cb3fdacffb890aeebdb0f5a3b6aaa7eeeaf1a38af0a8fe88b9e4b1f61f236d2e64d95733327a62@relay.ultrasound.money', 'Ultra Sound', True, 'Ultra Sound Relay')
  - ('https://0x8b5d2e73e2a3a55c6c87b8b6eb92e0149a125c852751db1422fa951e42a09b82c142c3ea98d0d9930b056a3bc9896b8f@bloxroute.max-profit.blxrbdn.com', 'bloXroute', True, 'bloXroute Max-Profit Relay')
  - ('https://0xa15b52576bcbf1072f4a011c0f99f9fb6c66f3e1ff321f11f461d15e31b1cb359caa092c71bbded0bae5b5ea401aab7e@aestus.live', 'Aestus', True, 'Aestus Relay')
  - ('https://0xb0b07cd0abef743db4260b0ed50619cf6ad4d82064cb4fbec9d3ec530f7c5e6793d9f286c4e082c0244ffb9f2658fe88@bloxroute.regulated.blxrbdn.com', 'bloXroute', True, 'bloXroute Regulated Relay')
  - ('https://0xac6e77dfe25ecd6110b8e780608cce0dab71fdd5ebea22a16c0205200f2f8e2e3ad3b71d3499c54ad14d6c21b41a37ae@boost-relay.flashbots.net', 'Flashbots', True, 'Flashbots Relay')

...

[bernatfp]

Need to update the README before merging