language search working, format search working, instant search working -> some tests still failing need to check that

Exercises should not depend on search,
so they get their own module.

This is done as to reduce the file size
and complexity of the exercise-details component.

This line was removed in a (foolish) commit
to development. It should remain in place,
otherwise the displayed hit count is messed
up when the search input changes.

Previously, hitCount was increased every time
a new batch of results was loaded.

Previously, hitCount was increased every time
a new batch of results was loaded.

added GitlabService.java to offer basic gitlab api functionalities like check if repo exists etc. , added check in StatisticsResource to avoid people sending get requests with IDs which not exist and therefore create lots of trash entities