fix(annotation): remove obsolete SelectedAnnotationState
fix(annotation): remove obsolete SelectedAnnotationState

This functionality was subsumed by TrackableDataSelectionState.

janelia-flyem/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,google/neuroglancer,google/neuroglancer,google/neuroglancer,janelia-flyem/neuroglancer,janelia-flyem/neuroglancer