Add ROI widget to the Plugin menu

[psobolewskiPhD]

This package permits saving ROI back to OMERO, per:
https://github.com/tlambert03/napari-omero#as-an-omero-cli-plugin
This adds a widget:

napari-omero/src/napari_omero/plugins/omero.py

Lines 102 to 110 in 5a23e26

	def add_buttons(viewer, img):
	"""Add custom buttons to the viewer UI."""
	def handle_save_rois():
	save_rois(viewer, img)
	button = QPushButton("Save ROIs to OMERO")
	button.clicked.connect(handle_save_rois)
	viewer.window.add_dock_widget(button, name="Save OMERO", area="left")

However this widget is not available from the napari plugin itself.

This widget would permit ROI loading from//saving to OMERO for an Image opened from OMERO.
In that regard, this is similar to #21

This would be an alternative to a Writer contribution which would make Save work for OMERO servers, see (outdated, but the gist): #20