Ghcide: ExceptionTests are incorrect

[fendor]

All exception tests are run in the ghcide directory, inferring a cabal cradle and failing, as the test files are not part of ghcide.
The tests themselves do not actually test what they set out to and merely increase the test suite execution time.

[fendor]

This issue shows that we should unify the test util infrastructure of ghcide and plugins.