Tests for proof tactics
Adding tests for proof tactics, since it seems we currently miss some errors during changes!
Progress:
Other changes to facilitate things:
:1st_place_medal: unwrapTactic
utility to call other tactics safely
Issues: The new tests in this PR will fail till I fix these (eventually)
LeftExists
checking
InstantiateForall
not working due to argument type mismatch -> changed it to accept a sequent and check against it