Update attestation APIs to support EIP-7549

[mehdi-aouadi]

Following the Electra containers updates:

• Update the /block and /pool attestation GET APIs to handle the new Electra attestations
• Add Electra.Attestation schema
• Extract the AttestationData schema used by both Attestation and Electra.Attestation
• Update the attester slashing API
• Update the IndexedAttestation schema

Partially fixes #445
Related to #447

[nflaig]

What about attestation event, should it be part of this PR?

beacon-APIs/apis/eventstream/index.yaml

Lines 64 to 68 in fb718b6

	attestation:
	description: The node has received an Attestation (from P2P or API) that passes validation rules of the `beacon_attestation_{subnet_id}` topic
	value: |
	event: attestation
	data: {"aggregation_bits":"0x01", "signature":"0x1b66ac1fb663c9bc59509846d6ec05345bd908eda73e670af888da41af171505cc411d61252fb6cb3fa0017b679f8bb2305b26a285fa2737f175668d0dff91cc1b66ac1fb663c9bc59509846d6ec05345bd908eda73e670af888da41af171505", "data":{"slot":"1", "index":"1", "beacon_block_root":"0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2", "source":{"epoch":"1", "root":"0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2"}, "target":{"epoch":"1", "root":"0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2"}}}

[mehdi-aouadi]

What about attestation event, should it be part of this PR?

beacon-APIs/apis/eventstream/index.yaml

Lines 64 to 68 in fb718b6

	attestation:
	description: The node has received an Attestation (from P2P or API) that passes validation rules of the `beacon_attestation_{subnet_id}` topic
	value: |
	event: attestation
	data: {"aggregation_bits":"0x01", "signature":"0x1b66ac1fb663c9bc59509846d6ec05345bd908eda73e670af888da41af171505cc411d61252fb6cb3fa0017b679f8bb2305b26a285fa2737f175668d0dff91cc1b66ac1fb663c9bc59509846d6ec05345bd908eda73e670af888da41af171505", "data":{"slot":"1", "index":"1", "beacon_block_root":"0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2", "source":{"epoch":"1", "root":"0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2"}, "target":{"epoch":"1", "root":"0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2"}}}

I considered the event stream events out of the scope of this PR. Might be addressed in a separate PR imo

[nflaig]

Haven't reviewed everything in detail but general approach looks good to me, let's get some feedback from others, especially in regard to having to bump everything to v2 or not

[rolfyone]

Yep I agree with new version for interfaces given they're a new required field (breaking) and headers.
minor comment about references to /dev versions.

[nflaig]

need to resolve conflicts since we merged #447