refactor: ♻️ Separate MSP and BSP specific functionalities in Blockchain Service

[ffarall]

This PR refactors some of the functionality in the handler.rs and utils.rs files of the Blockchain Service, to the new files handler_msp.rs and handler_bsp.rs. The goal is to keep BSP/MSP specific functionality better separated in the Blockchain Service.

[snowmead]

Nice job!

Future improvement: I suggest we separate the blockchain service command/event handlers by actor (MSP/BSP) as to avoid having all events and commands being implemented in a single place. It would be much clearer to the which actor is interested in.

It is clear though the separation of the two actors, but harder to maintain the codebase since the context is global.

if forest_root_write_result.is_ok() {
    match managed_bsp_or_msp {
        ManagedProvider::Msp(_) => {
            self.msp_assign_forest_root_write_lock();
        }
        ManagedProvider::Bsp(_) => {
            self.bsp_assign_forest_root_write_lock();
        }
    }
}

We can avoid this handling by having individual handlers for each actor.

[ffarall]

Future improvement: I suggest we separate the blockchain service command/event handlers by actor (MSP/BSP) as to avoid having all events and commands being implemented in a single place. It would be much clearer to the which actor is interested in.

@snowmead yeah I agree, I didn't want to over extend this PR, and the BSP/MSP specific commands was less of a problem in my view, than the other things I separated. But I agree, we can do that down the line too.