[Feature] Make `TransactionRequest` signable

[yash-atreya]

Component

rpc

Describe the feature you would like

Motivation

Currently a TransactionRequest cannot be signed using sign_transaction(signer), in order to do this we have to use the specific tx type we are trying to send from alloy_consensus. See: https://github.com/alloy-rs/examples/pull/129/files#diff-bd449423ea78c0a809dc015e99f4290e3ea5102dbcef24a70351ae6784a4f750R54-R79

Solution

Additional context

No response