Base implementation of the "Annotations Zoom View" in the Assembly Browser

Support base implementation of the Annotation Zoom View in the Assembly Browser.

The view should be based on the Zoom View of the Sequence View and located above the "Reference area". The unnecessary features (e.g. ruler, sequence, sequence selection, annotation selection, etc) should be removed. The current view should be synchronized with the over widgets of the Assembly Browser.

There are should be two ways to add annotations to the Assembly Browser:

1. to add annotations, associated with a reference sequence object
2. to add a separate annotation object, when some reference was already set.