Consistent colors for vega photometry plots

[scizen9]

Here is an initial try, but it only parses ztf filters. I have to work on a way to parse all the filters.

[scizen9]

Here's what it does so far:

[scizen9]

Attempting to address Issue #57 and Issue #681.

[acrellin]

@scizen9 What's the status here?

[dmitryduev]

@scizen9 any updates here?

You may want to use the same logic I used here for Centroid plots.

[acrellin]

@scizen9 What's the status here? Any way I can help?

[scizen9]

Vega lite issue still open.

[dmitryduev]

@scizen9 that issue is still open indeed, but it shouldn't be a showstopper here.
I implemented a workaround for the centroid plots, see here https://github.com/fritz-marshal/fritz/blob/master/extensions/skyportal/static/js/components/CentroidPlot.jsx#L108. There's a pre-defined set of key -> color mappings; if a given key is not found, a random color is used instead.

[acrellin]

@scizen9 Any updates here? According to Dima's comment above, this is currently doable. Thanks!

[acrellin]

@scizen9 Any updates here?

[profjsb]

@scizen9 please followup with Vega developers...

[dmitryduev]

@profjsb no need to do that -- see my comment above (I figured out what needs to be done in an older pr).

[mcoughlin]

Closing in favor of #2734.