Update stealthdrop in noir-examples

[critesjosh]

### Tasks
- [ ] Updating merkle tree implementation with zk-kit's version (passing in the bb poseidon hash function)
- [ ] Updating the example with a more recent-ish version of Noir
- [ ] Update the circuit to use poseidon2 as hash function instead of pedersen
- [ ] Finish the fronten
- [ ] Update the smart contracts
- [ ] PLUME integration

[critesjosh]

@signorecello are you able to pick this up or should we move it back to the backlog?

[signorecello]

I think this was on @jzaki ? But I see him with recursion, so maybe it was @catmcgee 😄 otherwise I wouldn't move it to the backlog, instead I'd discuss if we can finally hire some contractor to do the frontend for this. I'll add it to planning

[catmcgee]

think it was @jzaki because i was originally on recursion til alpha took my time! i can take this if @jzaki wants to continue on recursion

[jzaki]

Recursion PR ready for review 207