Implement pectra-devnet-4 changes

[yperbasis]

https://notes.ethereum.org/@ethpandaops/pectra-devnet-4

• [x] EIP-7251 address update: Done - https://github.com/ethereum/EIPs/pull/8889
• [x] Block body requests header update: Abandoned - https://github.com/ethereum/EIPs/pull/8908
• [x] Change to Engine API and block body for requests (flattening): TODO - https://github.com/ethereum/execution-apis/pull/591
• [x] Change deposit reqs to flat encoding: Done, needs changes - https://github.com/ethereum/EIPs/pull/8856
• [x] Change withdrawal reqs to flat encoding: In Progress - https://github.com/ethereum/EIPs/pull/8855
• [x] Change reqs hash to flat hash: Done, needs changes - https://github.com/ethereum/EIPs/pull/8854
• [x] Change consolidation reqs to flat encoding: Done, needs changes - https://github.com/ethereum/EIPs/pull/8857
• [x] Updated opaque requests: TODO - https://github.com/ethereum/EIPs/pull/8924
• [x] Change requests serialization: TODO - https://github.com/ethereum/EIPs/pull/8949
• [x] Update 7002 contract addr after logic update: Done - https://github.com/ethereum/EIPs/pull/8934
• [x] Update 7251 contract addr after logic update: Done - https://github.com/ethereum/EIPs/pull/8934
• [x] Implement changes for EIP-7702 and fix tests: Pending - https://github.com/ethereum/EIPs/pull/8948, https://github.com/ethereum/EIPs/pull/8929, https://github.com/ethereum/EIPs/pull/8938, https://github.com/ethereum/EIPs/pull/8845

v1.0.1 release of pectra-devnet-4 tests release at https://github.com/ethereum/execution-spec-tests already merged.

[somnergy]

Priority high here means importance, not all EIPs in the list have been merged/finalized yet for pectra-devnet-4. The issue is expected to remain open for some time till the EIPs are finalized. The code changes will be accumulated over multiple PRs referencing this issue.