feat: adding delegated voting using notes

[wei3erHase]

Created a PR adding a feature, not to be merged, or maybe, but to try to make a clear usage of custom notes, and how they can be used in this common implementation.

As voting, delegating will create the nullifier that avoids a msg_sender() from voting twice (not the best security against sybil attack, but well), and create a custom note, for the delegatee to use it and vote in the name of the user.

There are some features that would make it future complete and i'm researching how to implement them:

• test: create a test in JS, in which the delegatee actually sees the note creation from a secondary PXE (would need some orientation with this)
• doubt: is the randomness field in the note needed to avoid privacy leaking?
• feature: allow a delegator to batch vote delegations (doesn't seem that hard)

overall, discovered that .nr tests are amazingly fast and quite easy to setup, fear unlocked