Introduce deregistration period for provider/bidder registries

[shaspitz]

The validator registry contracts all have behavior where an actor needs to take an intermediate step for de-registration. They request dereg, wait a period of blocks (or time), then fully deregister with a second tx. See this example

mev-commit/contracts/contracts/validator-registry/VanillaRegistry.sol

Line 306 in 514339d

function _unstakeSingle(bytes calldata pubKey) internal {

.

This functionality needs to be added to the provider and bidder registries using already created libs

[ckartik]

This already exists, but we need to make sure the mev-commit node actually de-registers them when the stake is withdrawn.