Add Date term to KActivities Stats to filter on resource event date

Summary:
Add a Term Date to Query to filter on ResourceEvent start column when querying for resources.
Add two special cases : today and yesterday

Test Plan:
Manual through the test app
autotest

Reviewers: ivan, Frameworks

Reviewed By: ivan

Subscribers: kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D22717