Update color palette libraries for config and require 2+ colors

[julietcohen]

• Python version: 3.10.6
• Operating System: Ubuntu 18.04.6 LTS

Update color palette libraries

In the configuration file for the PDG workflow, we specify a color palette to apply during the rasterization step. The palettes are from the ColorAide and Colormaps libraries.

Examples of color palettes previously used:
"blue_medb717b"
"RdYlBu"
"RdBu"

These color palettes now return an error. As Robyn suggested, we should update the palette libraries. In the meantime, an example of an acceptable palette is: ["#d9c43f", "#d93fce"]

Require 2+ colors in palette

Additionally, consider returning an error message if the user supplies a palette with only 1 color. For example, "#d93fce". Palettes should be a range of colors to visualize data at each z-level.

Accessibility / Readability

We should consider that the default color palette used is colorblind friendly, or at least we flag or suggest color palettes to users that are colorblind friendly. Also, it would be great to add alt text wherever possible, such as for the plot viewer that we will eventually implement.

[westminsterabi]

I'd like to take this as my first issue, it's low priority but seems like low-hanging fruit :)