Add EIP: SSZ transactions root (#6404)

* Add EIP: Transition to SSZ

* Avoid CL/EL abbrev

* Cleanups from review

* remove block header conversion from scope

* remove security discussion from scope

* Update discussion link for new title

* Clarifying comment about why receipts don't have LC issue

* Update description

* Remove blob wrapper; Sync EIP-2718 nums; Helpers for non-tx; data-gas

* Fix section header

* Add `transaction_hashes_root`.

* rm fixed container capacity discussion from this EIP

* Convert to `BlobTransaction` for sighash/hash computation

* Further cleanup

* Align `SignedTransaction` field order with serialization

* Write permissions for Vitalik

* Update constants for `Receipt`

* Update `MAX_LOGS_PER_RECEIPT`

* Add rationale about `ReceiptLog` data.

* Remove merkle proof length from rationale

* rm `TxHashVersion`, rm EIP-155 type, rm extra tree

* rm `tx_hash` from `Receipt` for concurrent receipt/tx backfill (Geth)

* typo (ty @dapplion)

* Split away withdrawals (#6465)

* Split away receipts (#6466)

Author: etan-status