Staking Rewards

[jaybuidl]

### Tasks
- [ ] #735
- [ ] #265 
- [ ] #658 

[greenlucid]

There's a missing activity: pnk-merkle-drop (or rather, the pnk-merkle-drop-v2 we build onto the kleros-v2 monorepo) needs to be made compatible with v2 interface, events, etc. There might even be a decision to make, regarding dispute kits: do we want to only support staking on particular "dispute kits" courts? (I'm not familiar with how this system works yet, just stating that it's not straightforward)

I assume, we would simply target the "vanilla" kleros dispute kit and distribute rewards in there. But, I'm just making sure.

Otherwise, the frontend logic will be similar to v1, and the merkle drop contract should be the exact same, excluding

Maybe, since the frontend does not directly interact with the script that is generating the PNK reward snapshots, writing the scripts to generate the PNK could be done last?

There's an ugliness I would like to address: the way we currently do it at V1, is generate the snapshot, upload to ipfs, send the PNK to the merkle contract, and then manually (with a PR like this) add the ipfs links to the snapshots to a file in the court frontend. Maybe, since we're already rethinking this, we could use a slightly different merkle contract in which we also pass the ipfs link so that's emitted, and then we don't need to pollute the repo with manual monthly additions of snapshots