Upstream tx size-ish checks from Consensus

Since https://github.com/IntersectMBO/ouroboros-consensus/pull/1175, the Mempool needs to be able to run all size-related checks (tx byte size, execution units, ref scripts) separately from (namely before) regular tx validation. Currently, this logic is implemented in Consensus (in [`Ouroboros.Consensus.Shelley.Ledger.Mempool`](https://github.com/IntersectMBO/ouroboros-consensus/blob/main/ouroboros-consensus-cardano/src/shelley/Ouroboros/Consensus/Shelley/Ledger/Mempool.hs#L22-L24), but this rather belongs into the Ledger, where it can be shared with the regular tx validation.