This commit introduces changes related to vault registrations in the
stake manager.
The stake manager needs to keep track of the vaults a users creates so
it can aggregate accumulated MP across vaults for any given user.
The `StakeVault` now comes with a `register()` function which needs to
be called to register itself with the stake manager. `StakeManager` has
a new `onlyRegisteredVault` modifier that ensures only registered vaults
can actually `stake` and `unstake`.
Closes#70
This function allows users to `leave()` the system if they can't or
don't want to trust the stake manager. This is the case when the owner
of the stake manager performs an upgrade.
In case of such an upgrade, the stake manager will be marked as not
trusted which prevents the user from staking, unstaking, locking etc.
The user can then either explicitly trust stake manager (will happen in
future changes) to enable the vault's functionality again, or, `leave()`
the system at which point it will try to perform a benign `leave()`
operation and then move the funds out of the vault.
Closes#66
This commit introduces upgradeability of the `RewardsStreamerMP`
contract by leveraging the UUPS pattern.
This means, for deployment, we have to first deploy an instance of
`RewardsStreamerMP` contract as a "template" logic contract and then
create a ERC1967Proxy that points to it.
The proxy ensures the implementation address is stored in a
deterministic storage slot.
This will later be leveraged by the `StakeVault` contract to implement
the functionality to leave the system in case there was a malicious
upgrade.
Closes#22
