Native staking changes

[naddison36]

Contract Changes

• Native Staking Strategy now holds consensus rewards as ETH. All WETH is now from deposits.
• FeeAccumulator now holds execution rewards as ETH
• Removed WETH immutable from FeeAccumulator
• Converted custom errors back to require with string
• collectRewardTokens now converts ETH to WETH at harvest
• checkBalance is now validators * 32 plus WETH balance from deposits
• Renamed beaconChainRewardsWETH to consensusRewards
• Fixed bug in stakeETH that was converting all WETH to ETH

Accounting for ETH rewards and withdrawals

[github-actions[bot]]

	Warnings
:warning:	:eyes: This PR needs at least 2 reviewers

Generated by :no_entry_sign: dangerJS against 30cd24069e5cc7a2785fecda0240e33be1a8fd5e