Electra spec testing

[ralexstokes]

Collecting some testing items to track for Electra:

EIP-7549

• revisit tests once we decide how to handle 353bbb0
• revisit the 'randomization' tests, to ensure we have good coverage across all operations types and scenarios

[hwwhww]

• new partial withdrawal tests

[hwwhww]

pytest coverage report results. to be investigated:

Beacon chain

• apply_deposit
  • 
• switch_to_compounding_validator
  • 
• queue_excess_active_balance
  • 
• process_withdrawal_request
  • 
• upgrade_to_electra - if has_compounding_withdrawal_credential(validator)
  • 

Validator guide

• get_eth1_pending_deposit_count