Reactor: Decoupling pool-registry from pool-system and pool-fees

[lemunozm]

Description

The intention of this PR is to clean the mess we currently have when testing/benchmarking pool things from pool-registry PoV. Almost no production logic is touched, only for cases that affect the benchmarking

NOTE: Current tests do not cover everything, but they cover what the same they covered before the refactor.

Changes and Descriptions

• Remove all pool-related dependencies from pool-registry (look at the mock.rs file!)
• Added BoundedVec when needed to carry the Max information associated to those vecs
• Remove PoolMetadata trait which is not used.
• Simplify weight computation by removing some unused extra params.
• Based of this comment I removed the capability of update & execute in the same call, which is impossible to be used right now in the runtime, and in case of required, it can be batched. Tell me if you agree or I revert.
• Reorganize benchmarking traits (WIP)
• Other minor simplifications

Still WIP

• Correct reorganization of benchmark traits/methods
• Fix execute_update benchmark