EIP-4881: Deposit Contract Snapshot Interface

[twoeths]

Is your feature request related to a problem? Please describe.

Currently we have to always fetch all historical deposits, even through we do a weak subjectivity sync. This enhancement supports extracting and downloading a compressed merkel tree that's enough to produce deposit proofs (in order to produce blocks), and we can build our partial merkle tree from there

Refer to https://eips.ethereum.org/EIPS/eip-4881

Describe the solution you'd like

• Implement Deposit Contract Snapshot beacon api https://github.com/ethereum/beacon-APIs/pull/245/files . This depends on Snapshot apis ssz#293 , this is likely for the public apis we already have.
• Consume it when doing weak subjectivity sync
• Prune deposit root tree when Eth1Data is considered finalized

[dapplion]

@tuyennhv Please note that this mechanism will likely become obsolete soon once the deposit processing is moved from a bridge structure to in-protocol -> ethereum/consensus-specs#3177

[dapplion]

Closing for #5561

[AkshatGada]

Can I be assigned to solve this issue , I am working on it since several days .