feat(script): add deployment script for new StakeManagers

[0x-r4bbit]

This is needed to deploy individual new StakeManager instances in both, production environment and testing.

The script can be used as follows:

Within tests, to get a new StakeManager instance that has a reference to an older StakeManager instance, run:

function setUp() public virtual override {
    super.setUp();
    DeployMigrationStakeManager deployment = new DeployMigrationStakeManager(address(stakeManager), stakeToken);
    newStakeManager = deployment.run();
}

Where address(stakeManager) is the address of the current StakeManager and stakeToken is the address of the stake token.

To deploy a new instance from the CLI using forge, one can make use of the PREV_STAKE_MANAGER and STAKE_TOKEN_ADDRESS environment variables like this:

$ PREV_STAKE_MANAGER=0x123 STAKE_TOKEN_ADDRES=0x456 forge script script/DeployMigrationStakeManager.s.sol

The script will revert when STAKE_TOKEN_ADDRESS is address(0).

Closes #71

Checklist

Ensure you completed all of the steps below before submitting your pull request:

• Added natspec comments?
• Ran forge snapshot?
• Ran pnpm gas-report?
• Ran pnpm lint?
• Ran forge test?
• Ran pnpm verify?

[0x-r4bbit]

Theoretically, we can extend this and say, if prevStakeManager != address(0), then we query the stakeToken() address from the old manager.

[0x-r4bbit]

Another thing I've just realised, it probably makes sense to extend this so that it automatically activates migration in the old manager.

If we make this part of this script, however, it's probably less usable in the testing context (which I think would be fine, as in tests we can always just do new StakeManager() individually.

Let me know what you think.