feat: Introduce NodeBuilder

[Rjected]

This implements the node builder designed in #5693, and adds a simple block number test with the following UX:

// this launches a test node with http
let rpc_args = RpcServerArgs::default().with_http();
let handle = spawn_node(NodeBuilder::test().with_rpc(rpc_args)).await.unwrap();

// call a function on the node
let client = handle.rpc_server_handles().rpc.http_client().unwrap();
let block_number = client.block_number().await.unwrap();

// it should be zero, since this is an ephemeral test node
assert_eq!(block_number, U256::ZERO);

TODO:

• Fix tests - we currently install the prometheus recorder more than once if we spin up multiple nodes in a test

For follow-up:

• Provide a handle method for shutting down the node. It might also need to run when all handles are dropped?

Fixes #5693

[mattsse]

this is great!

I like this a lot.

I have a few ideas for followups, but these will be related to better node type abstraction.

with the builder we now have the flexibility to make incremental changes.

as immediate followup, I suggest we refactor the bin/reth crate layout:

group commands in commands folder,

move NodeBuilder and related to node, this is prep for extracting that code to a standalone repo

[mattsse]

I like this a lot.

this unblocks more generalization.
we can now make more incremental changes and improve extensions and UX