Heavily comment the `integration_test_lib` and `test_executive`

[Isaac-DeFrain]

Problem There are very few comments in the integration_test_lib. This makes the learning curve too steep.

Assessment Criteria Commonly used testing functions will have numerous comments to aid test writers.

Tasks

• [ ] Add comments to Intf module values, types, modules, and signatures
• [ ] Add comments to Dsl module values, types, modules, and signatures
• [ ] Add comments to Test_config module values, types, modules, and signatures
• [ ] Add comments to Malleable_error module values, types, modules, and signatures
• [x] Add comments to Test_common module

[Isaac-DeFrain]

WIP PR for Test_common and integration test improvements https://github.com/MinaFoundation/mina/pull/18