Test Adequacy interaction with JSON Frontend

[christopher-wild]

The current implementation of checking test adequacy with the JSON frontend works but should be refactored if possible.

However this will likely depend on the work with #210

1. Should test adequacy be on a per test basis or an argument for the entire JSON test set?
2. To avoid writing implementation code inside the JSON frontend, where should the call to the new DataAdequacy class come from?

[jmafoster1]

@f-allian how is this being handle by the new frontend? I'm not against having, e.g. a -a argument at the top level to calculate test adequacy for every test rather than specifying it per test case in the JSON.