chore(rpc): EthApi builder

[emhane]

Closes #8986

• Adds trait EthApiBuilder for building custom RPC server for eth namespace
• Rename RethModuleRegistry to RpcRegistryInner, coherent with other rpc types.
• EthApiBuilder only stored as trait object in type in reth-rpc-builder, and is constrained by the server type it builds. The server type built is inherited from node builder.
• Removes unused fields from RpcRegistryInner. set_eth_raw_transaction_forwarder has been removed with precaution: on main, the only way to add the tx forwarder outside of module, is via method RpcRegistryInner::set_eth_raw_transaction_forwarder, so it's safe to build EthHandlers in RpcRegistryInner constructor with field set to None in EthApiServer type.

[emhane]

re-request review @mattsse

[mattsse]

I like the direction, this is basically a builder trait for the EthApi.

I'd like to make this consistent with the other builder traits we already use

reth/crates/node/builder/src/components/pool.rs

Line 7 in 6d8cbae

pub trait PoolBuilder<Node: FullNodeTypes>: Send {

but not generic over types and instead:

reth/crates/node/builder/src/rpc.rs

Line 33 in 6d8cbae

pub(crate) struct RpcHooks<Node: FullNodeComponents> {

[mattsse]

gotcha, then this is the next intermediary step towards nodebuilder integration and we need need to take a look at how to separate rpc-builder from node-builder, or at least separate the node-builder internal traits

[emhane]

I simplified this based on latest review and general goal of configuring relevant rpc modules in node builder.

next methods to work on in reth-rpc-builder scope are RethRegistry::reth_methods, RethRegistry::module_for and RethRegistry::maybe_module. rn they are the funnel through which it is required for the configured EthApi type to impl FullEthApiServer - which is a shame for users who just want to enable the AdminApiServer for example, or EthApiServer but without calling tracing methods.

I think it makes sense to continue in the node builder scope next. let's get the code in place required to add certain modules, even though rn it will be required that the configured EthApi type supports adding all modules (even if user just wants to add one little module).

[mattsse]

last nits, questions.

this should unblock us from integrating this in node-builder and creating an op impl

[mattsse]

last naming nit