Add ROIs from OMERO - workflow improvements

[will-moore]

Discussed with @pwalczysko based on feedback from recent workshops, cc @jburel

Current problems:

• You can't add an ROI to a panel if the ROI is outside the viewport of that panel. If you zoom out to show the whole image, for a Big Image this means that the ROIs you add are vanishingly small, and you can't then zoom back in to show the ROI.
• Even if you have zoomed-in to the correct region, it's hard to pick ROIs by mousing over then in the table (and seeing them briefly overlaid on the image). What you really want is to see them all on the Image, and to pick them from there. NB: The existing workflow doesn't add them all to the Image initially because you'd get these "temporary" shapes mixed-up with the Shapes that are actually already on the Image (that you might be editing). You kinda need 2 modes: "Editing" and "Adding from OMERO".

Current UI:

Solution:

• When you load ROIs from OMERO, show them all on the image and pick them from there. E.g. select a few (toggle selection by clicking on them) then "Add".
• When you click on an ROI in the table (list), the viewport should pan (and zoom) to show that Shape. Then you can click it on the Image to select it for Adding.
• "Select All" option could select all that are in the current viewport.