Feature Request: add eth_sendRawTransaction RPC to the relay

[thegostep]

Adding the eth_sendRawTransaction RPC would make it easier for applications like metamask to directly support private transactions.

A transaction sent through this endpoint would be merged with other transactions / bundles on the relay or on mev-geth.

Open questions:

• Should the transactions revert on chain? Not reverting on chain would save chain space, but make it difficult to define a policy for when the transaction should be dropped from the private mempool.