Contract runtime suppression

[rkolesnev-vineti]

Sometimes we need to suppress contracts on the runtime level. Unfortunately, contracts are not free in a performance sense.

Draft API:

# Global suppression
Flows::Contracts.supress do
  # any contract execution is suppressed here, transformations are not applied
end

# Output contract local suppression
OperationWithContract.without_output_contract # => returns child class with output contract disabled.