Remove enveloped_tx from TxEnv

[Rjected]

Related to #991

ref paradigmxyz/reth#6008 (comment)

Currently, the entire enveloped tx is used to calculate the optimism L1 tx cost, which is overkill given that the op-geth cost function acts on two fields:

// RollupCostData is a transaction structure that caches data for quickly computing the data
// availablility costs for the transaction.
type RollupCostData struct {
	zeroes, ones uint64
}

This should also be changed in the optimism version of the tx env.

[rakita]

Just to link the issue, the Generic Tx trait is a solution for this: #916