Fix runner freezes, make script jobs abortable

Create ProvidersDataSource object in data engine constructor,
to ensure it is always available, needed very often.
Initialize as 'dirty' to fill with provider data.
Also create the file system watcher in the constructor.

Implement ScriptJob::requestAbort(), like TimetableMate's
DebuggerJob::requestAbort(). Keep track of running jobs in
ServiceProviderScript, in the destructor abort all running jobs and
give them maximally one second to finish. The previous
ThreadWeaver::Weaver::instance()->finish() waited for all script jobs
from any provider also if there was no job running at all.
That could freeze krunner, when typing "too fast"