introduce Block trait abstraction

[mattsse]

we need to gradually introduce traits for the block type

this should leverage alloy traits where it makes sense (e.g. Transaction trait or Encodeable)

First step is introducing the associated types

reth/crates/node/types/src/lib.rs

Line 22 in 0845c7f

pub trait NodePrimitives {}

in a follow we can further enforce and restrict this to reth_primitives types at first, like we currently do with the unified ChainSpec type before we move to traits entirely.

ref #9029 for an initial draft, we need a Block trait that contains a body type, the body then contains the transactions. This way we can design the body as we like (e.g. withdrawals, requests, etc..)