This implements a helper to get the ptc committee from a state. It uses
the cached beacon committees if possible

It also implements a helper to compute the largest power of two of a
uint64 and a helper to test for nil payload attestation messages

* Add ePBS to db

* Modify `get_ptc` function to follow the Python spec

* Assign PTC members from the beginning of beacon committee array

* Add `remove_flag` and its unit test

* Add a test case trying to remove a flag that is not set

* Ensure EPBS state getters and setters check versions

* Rename to LatestExecutionPayloadHeaderEPBS

* Add minimal beacon state

* Add `IndexedPayloadAttestation` container

* Add `GetPayloadAttestingIndices` and its unit test

* Add `GetIndexedPayloadAttestation` and its unit test

* Add `is_valid_indexed_payload_attestation` and its unit test

* Create a smaller set of validators for faster unit test

* Pass context to `GetPayloadTimelinessCommittee`

* Iterate `ValidatorsReadOnly` instead of copying all validators

* Allow nodes with and without payload in forkchoice

    This PR takes care of adding nodes to forkchoice that may or may not
    have a corresponding payload. The rationale is as follows

    - The node structure is kept almost the same as today.
    - A zero payload hash is considered as if the node was empty (except for
      the tree root)
    - When inserting a node we check what the right parent node would be
      depending on whether the parent had a payload or not.
    - For pre-epbs forks all nodes are full, no logic changes except a new
      steps to gather the parent hash that is needed for block insertion.

    This PR had to change some core consensus types and interfaces.
    - It removed the ROBlockEPBS interface and added the corresponding ePBS
      fields to the ReadOnlyBeaconBlockBody
    - It moved the setters and getters to epbs dedicated files.

    It also added a checker for `IsParentFull` on forkchoice that simply
    checks for the parent hash of the parent node.

* review

* Read only payload attestation message with verifier

* Payload attestation tests (#14242)

* Payload attestation in verification package

* Feedback #1

---------

Co-authored-by: Md Amaan <114795592+Redidacove@users.noreply.github.com>

)

* Add `execution_payload` and `payload_attestation_message` topics

* Set `SourcePubkey` to 48 bytes long

* Add randomly populated `PayloadAttestationMessage` object

* Add tests for `execution_payload` and `payload_attestation_message` topics

* test-added

* nil check fix

* randomized inputs

* hardcoded inputs

* suggestions applied

* minor-typo fixed

* deleted

Adds the processing of execution payload envelope
Corrects the protos for attestations and slashings in Electra versions
Adds generators of full blocks for Electra

* Payload Attestation Sync package changes

* With verifier

* change idx back to uint64

* subscribe to topic

* add back error

---------

Co-authored-by: terence tsao <terence@prysmaticlabs.com>

* Add getter for payload attestation cache

* Check against status

* Feedback #1

* Enable validator client to sign execution header

* Update proto/prysm/v1alpha1/validator-client/keymanager.proto

---------

Co-authored-by: Potuz <potuz@prysmaticlabs.com>

* process_withdrawal_fn and isParentfull test

* suggestions applied

* minor change

* removed

* lint

* lint fix

* removed Latestheader

* test added with nil error

* tests passing

* IsParentNode Test added

* lint

* fix test

* updated godoc

* fix in godoc

* comment removed

* fixed braces

* removed var

* removed var

* Update beacon-chain/core/blocks/withdrawals.go

* Update beacon-chain/core/blocks/withdrawals_test.go

* gazelle

* test added and removed previous changes in Testprocesswithdrawal

* added check for nil state

* decrease chromatic complexity

---------

Co-authored-by: Potuz <potuz@potuz.net>
Co-authored-by: Potuz <potuz@prysmaticlabs.com>

* Enable validator client to sign execution payload envelope

* Update comment

Co-authored-by: JihoonSong <jihoonsong@users.noreply.github.com>

---------

Co-authored-by: JihoonSong <jihoonsong@users.noreply.github.com>

* Correct requirement list of EnvelopeVerifier

* Add unit tests of ExecutionPayloadEnvelope verification

* Signed execution payload header for sync

* Use RO state

* SignedExecutionPayloadHeader by hash and root

* Fix execution headers cache

* Handle incoming ptc attestation messages in the chain package

* fix double import

* remove unused error

Add wait until PTC duty

…14450)

* Share resources between empty and full nodes

- Share a block structure withing the forkchoice node. The surrounding
  envelope contains information about the payload presence and the
  children links, the inner structure contains the usual FFG and parent links.
- Reworked setOptimistictoInvalid
- Changed the PTC vote logic to have validity handled outside of
  forkchoice and have forkchoice only keep the total count of votes.

* Fix tests

* gazelle

* Update head twice pre-epbs

* only upadte best descendants without computing head

* skip forkchoice tests

* fix some blockchain tests

* Nil optimistic sync fix

* only count weight of empty nodes

These are some of the things that are left to be done

    - Process the payload
    - Change stategen to get the poststate of the block and the payload
      separately
    - Change the next slot cache to be safe for full/empty