Before- and after-test hooks

[mikekeke]

Tasty-putip framework enhancement proposed by @TotallyNotChase.
Idea is to provide integration hooks that could be run before and after test group execution. The key feature this hooks is the ability to span through several test cases. For example, beforeAll would be a function that takes a setup function, and a test group, it runs that setup before any tests in the test group, obtains the result and makes it available for each test in the test group.

Current implementation can be checked out here:
https://github.com/bladyjoker/plutip/tree/integration-hooks
Most of related changes are in Test.Plutip.Contract, Test.Plutip.LocalCluster, and Test.Plutip.Contract.Types.