Handle fee recipients for the different DVT/LSD protocols

[dsimog01]

We need to handle the fee recipients for the protocols that need a fix address for this field. For example, rocketpool asks all the users to have the same fee recipient, but others depend on the pool in which the user participates. Some others might also give more flexibility on this topic.

We should research how each of these work in order to allow the automatic import via launchpad API of the brain. One option to consider is to use a validator pubkey to get the fee recipient associated to it, but his may not be available for all the protocols

[dsimog01]

Fee recipients	Changeable?	How to handle from backend?	Value
Rocketpool	No
Stakehouse
Stakewise v3
Solo
Obol