Refactor SliceSelections ids propagation

[palucdev]

Current Behavior

Slice selections IDs are auto incremented and set when new SliceSelection object is created. It is now coliding with Brush/Eraser Selector and in future can cause problem with other new tools.

Expected Behavior

We should use service that will keep track of IDs. Using this kind of component we can get next id, reset id counter and other possible id operations. Without auto ids we can create objects that will reuse other id without incrementing id pool.

Additional comment (optional)

Connected with #397