checked/unchecked now uses containsAll/One

Methods for adding and removing games based on checking/unchecking tags
now utilizes ContainsAll and ContainsOne methods.
- Made getting the TagApplicationMethod into a helper method called
"GetTagApplicationMethod()".
- Unchecking tags should now properly look at if games are installed IF
Only Installed is checked.
- Checking Only Installed has new logic to work with the new current
implementation.