Implement and modify beacon chain functions: Epoch processing, Beacon state accessors, compute_proposer_indices and BeaconState

[Kayden-ML]

Describe the feature

This issue should Implement the new functions introduced and listed below and modify the existing functions listed below

• Implements compute_proposer_indices(): https://ethereum.github.io/consensus-specs/specs/fulu/beacon-chain/#new-compute_proposer_indices
• Modifies get_beacon_proposer_index(): https://ethereum.github.io/consensus-specs/specs/fulu/beacon-chain/#modified-get_beacon_proposer_index
• Implements get_beacon_proposer_indices(): https://ethereum.github.io/consensus-specs/specs/fulu/beacon-chain/#new-get_beacon_proposer_indices
• Modifies process_epoch(): https://ethereum.github.io/consensus-specs/specs/fulu/beacon-chain/#modified-process_epoch
• Implements process_proposer_lookahead(): https://ethereum.github.io/consensus-specs/specs/fulu/beacon-chain/#new-process_proposer_lookahead
• Modifies BeaconState: https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/beacon-chain.md#beaconstate

[AnInsaneJimJam]

@Kayden-ML Can I work on this too?

[AnInsaneJimJam]

I opened a draft PR #1065 . It's failing some test due to proposer lookahead field. Can you share some insight over this @Kayden-ML . I just read the code in python in specs and wrote in rust .

[shariqnaiyer]

The spec tests we are using have not been updated to Fusaka as far as I am aware. They are expected to fail on your PR at the moment. Do not be deterred by failing tests.

I am looking into the changes regarding proposer lookahead 👍

[AnInsaneJimJam]

So should I add PR now or wait for the test to pass?

[shariqnaiyer]

Make a PR if you believe your changes are ready for review. If the tests are not passing due to a compatibility issue across forks, we will debug that and make a decision prior to merging it.