Firefly-1889: update table row viewer with improved masking

[robyww]

Firefly-1889: update table row viewer with improved masking

• fix issues with TableRowViewer masking that was not right in my last PR
• Create a more PlotView like look during working
• refactor working task management to work better with promises
  • task are added with promises that are removed when the promises fulfills. The is not longer a remove task call.
  • removed code that is now unnecessary

Testing

• https://firefly-1889-masking.irsakubedev.ipac.caltech.edu/applications/spherex
• Every should work with better PlotView like masking when sliding.

[kpuriIpac]

I looked at the old PR and this PR. It's of course a complex component, code would probably be better reviewed by @jaladh-singhal when he's back (not blocking for this PR, I just mean in a future iteration of work with this code).

I think the masking is working better, but I did notice a few small issues:

This looks. fine as Searching Images is centered here. But after these images load, and you slide right by a few images really quick, you may get something like:

I am not suggesting this necessarily needs fixing, but just wanted to highlight it (the fact that only the image on the far right says Searching Image)

Looks good other than that!

[kpuriIpac]

Looks good! Spent time trying to study code in the old PR and this one. Might need a deeper review eventually as well, but looks good to me.