Minimal add tags to ROI functionality

[will-moore]

See https://forum.image.sc/t/tag-an-individual-roi-shape/105166/3

Initial investigation towards answering the question "how long would it take" to implement ROI Tagging in iviewer...

This is a BARE MINIMUM viable working prototype:

• You need to save ROIs first, and you also need to have created Tags already and know the Tag IDs, as the most challenging part of a full solution is to load and select the Tags.
• If you choose the Show ROI Tags column of the ROI table, it will load existing Tags on the ROIs - see screenshot. NB: only loads Tags for up to 500 ROIs just now. To support more we would probably need to batch request.
• If you mouse-over you can see the ID of each Tag in the tooltip. Otherwise you'll have to copy Tag IDs from the Tag page of webclient.
• If you type a valid Tag ID you want to add in the input field and hit Enter, it will be added to the ROI and displayed.
• No functionality for removing Tags yet, but wouldn't be hard to add.

This work took about 3 hours - maybe a bit more as it took me a while to remember how Aurelia framework works!

[imagesc-bot]

This pull request has been mentioned on Image.sc Forum. There might be relevant details there:

https://forum.image.sc/t/tag-an-individual-roi-shape/105166/5