Release 0.12.0

Upgrade procedure
- The release must be applied via cosmovisor and Upgrade Proposal transactions, see pool-upgrade-how-to.md.
- The upgrade name must be equal to v0.12.0.
- The release must be applied to all nodes (Validators, Observers, Sentries, etc.)
- All upgraded nodes must be at 0.11.0 with cosmovisor enabled.
- It's recommended to enable the auto-download for cosmovisor on all nodes, see pool-upgrade-how-to.md.
Adding new nodes to the running pool (Test Net in particular) must be done via one of the ways described in running-node-in-existing-network.md. Starting a new node from the genesis state will not work. There are instructions on how to add a new node to the Test Net:
- Running Node Index with examples for the Test Net
- Adding new Observer nodes to Test Net
- Adding new Validator nodes to Test Net

Major Changes (comparing to 0.11.0)