The integration tests are currently not consistent in how they do
copy/pasting: some tests use the `kbCopy`/`kbPaste` functions with
waiting for the event inline, some have their own helper function to
combine those actions and some even call `kbCopy`/`kbPaste` without
waiting for the event at all (which can cause intermittent failures).
This commit fixes the issues by providing a set of four helper functions
that all tests use and that abstract e.g. waiting for the event away
from the caller. This makes the invididual tests simpler and consistent,
reduces code duplication and fixes possible intermittent failures
due to not waiting for events to trigger.
