[multidelegation] feat: multidelegation strategy

[ncomerci]

Changes proposed in this pull request:

• Added support for users to delegate to multiple addresses

[ChaituVR]

Hey guys, i feel like this is too heavy for us, we stopped adding new strategies that depend on other voters https://github.com/snapshot-labs/snapshot-strategies#code do you think of any other alternatives? maybe you can run this on our side and use api-v2 strategy to return the voting power (if there is no need for override)?

[zzuziak]

Hey everyone! We discussed with @bonustrack and decided to proceed with a custom Voting Strategy implementation with overriding instead of using the api strategies. @ChaituVR can you do a final check on the PR and we can merge?