feat: pectra compatability

[ypatil12]

Updates checkpoint proof system to be Pectra compatible. The breaking change to EigenPods is the BeaconState container increasing to have 38 fields, which results in the tree height to be > 5.

EigenPodManager

• Added a setPectraForkTimestamp method in the EPM that is callable only once
• Added a getPectraForkTimestamp method

EigenPod

• Updated balance container and validator container proofs to pass in a proof timestamp to check against which tree height to use for the beacon state
• Note that since the 4788 oracle returns the PARENT beacon block root, our check against the pectra fork timestamp returns the previous tree length for proofs that are <= pectraForkTimestamp

Deprecation Plan

• Post pectra, we can upgrade the EigenPod to deprecate the fork timestamp case handling once all in progress pre-Pectra checkpoints have been completed

TODOs

• Unit Tests
• Integration Tests simulating upgrade
• Mekong Deployment