[Merge] Make Teku interop standalone node running with stubbed Execution Engine

[Nashatyrev]

PR Description

Build on top of #4423

With this PR merged standalone (all validators on a single node, no networking) interop Teku node could be running and finalizing beacon chain. Execution Engine is just stubbed.

Generating genesis state:

> teku genesis mock \
  --output-file ./local-genesis.ssz \ 
  --network=minimal \
  --Xnetwork-altair-fork-epoch=0 \
  --Xnetwork-merge-fork-epoch=0 \
  --validator-count=256

Running a node:

> teku \
  --Xinterop-enabled=true \
  --Xinterop-number-of-validators=256 \
  --Xinterop-owned-validator-start-index=0 \
  --Xinterop-owned-validator-count=256 \
  --network=minimal \
  --Xnetwork-altair-fork-epoch=0 \ 
  --Xnetwork-merge-fork-epoch=0 \ 
  --p2p-enabled=false \
  --initial-state ./local-genesis.ssz

Fixed Issue(s)

Documentation

• I thought about documentation and added the documentation label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

[tbenr]

LGTM