feat(payload): add support for multiple payload builders in BasicPayloadJobGenerator

[aroralanuk]

Problem

We need a flexible way to combine and sequentially execute multiple payload builders of the same type, allowing for more complex and customizable payload building strategies. Fixes #10438

Solution

Implement a new PayloadBuilderStack<B> that can hold and execute multiple builders of type B in sequence.

Implementation Details

• Create PayloadBuilderStack<B> with a single generic type parameter
• implement the same PayloadBuilder trait methods for the stack struct
• Implement sequential execution of builders for try_build, on_missing_payload, and build_empty_payload

Open question

• PayloadBuilderStack is designed to be a drop-in replacement for any single PayloadBuilder implementation, where will it be actually used in reth?
• Do you want me to propagate the error if we encounter one in a specific builder or just continue with other builders?
• Is falling back to MissingPayloadBehaviour::AwaitInProgress ok for on_missing_payload?
• What kind of tests should I add to test this feature?

Testing

• None

[nkysg]

no just something that wraps two instances of the same kind (ethereum eg)
similar to https://docs.rs/tower/latest/tower/layer/util/struct.Stack.html
the idea here is that you can use two diff payload builders
and the attributes would be an Either<A, B> where A,B are the payload attributes types of the respective payload builders

Originally posted by @mattsse. FYI @aroralanuk

[Rjected]

I think the original issue requested a stack where you could use more than one type of payload builder - in this, because of the single generic, you can only do multiple of one type of payload builder. So this needs to be changed to support two different payload builders with two different types