Add schema / flexibility to HistomicsUI to allow filtering/display of only certain metadata fields and annotations/ROIs

[dgutman]

We can currently add/view metadata in the HistomcsUI interface, but it only allows key/value pairs. Similarly, it will by default display all metadata associated with a given item.

I propose that we add a "magic" item like .histomicsUIMetadata (or similar) that the frontend can parse that would allow the following functionality.

1. Show only a subset of metadata fields by default

2. Potentially allow "all" metadata to be viewed as a popup or something, but not shown by default

3. While on the backend we store key/value pairs, allow additional controls for how a given item/key is editable in the UI.. I.e. we could limit things so we have sliders, combos, enumerable fields, whatever. This is an important feature for USER studies as we can then limit options/input for certain user studies.

4. Since many of our annotation projects are ROI focused, it would be good to add functionality that when a user opens an item in the UI, we have some REGEX/pattern that will scan all of the annotations currently associated with a slide and this would allow ROI's to be "turned on" automatically. This prevents a user having to find the ROI in the annotation and then turn it on and should simplify things a lot for end users.