* Simplify submit_and_watch_signed_extrinsic

The way submit_and_watch_signed_extrinsic is used now, we can always
derive the SignParam from other params. If in the future we need more
customization possibilities, we can define a new method.

* Simplify submit_signed_extrinsic

* Send maybe_batch_tx as a parameter

Send `maybe_batch_tx` as a parameter to `submit_proof()`. This way we
can deduplicate the logic that submits the extrinsic for
`messages_source and `messages_target` and we can simplify the logic in
the race loop a bit.

* Define BatchProofTransaction

Deduplicate BatchConfirmationTransaction and BatchDeliveryTransaction by
replacing both of them with BatchProofTransaction

* Define ChainWithUtilityPallet and BatchCallBuilderConstructor

- Define `ChainWithUtilityPallet` in order to be able to associate the
  batching functionality with chains
- Defining `BatchCallBuilderConstructor` in order to have a more reliable
  way of checking whether an end of a messages pipeline supports batching
  or no. `BatchCallBuilderConstructor::new_builder()` returns an
  `Option<BatchCallBuilder>`.This is a bit safer because each time a caller
  tries to start creating a batch call, it will call `new_builder()` and
  will be required to handle the returned `Option`. Before we only had a
  bool `BATCH_CALL_SUPPORTED` the caller could have forgetten to check.