Ability to add custom color palettes

[heidimok]

• stac ipyleaflet version: for release 0.3.0
• Python version: python >= 3.9 (some of the widgets are incompatible at v 3.8)
• Reference column Number 4 in the MAAP-ipyleaflet-DevRoadmap

Context

Release 0.2.0 of stac_ipyleaflet allows users to select a cog from a collection in the STAC data catalog and pick from color options.

We are currently using https://matplotlib.org/stable/tutorials/colors/colormaps.html

Problem

Though there are many color options available, sometimes a scientist doesn't want to only pick from those options for the map. It's not just about opacity but what a layer looks like (chloropleth or isopleth).

Acceptance Criteria

• A way for users to add their own colors

[heidimok]

Design Iteration 1

• Adding first iteration here for discussion (see figma)

• The idea builds off of changes to the layout from Consolidate UI of Layer and STAC widgets #63

• Wherever the color palette option exists, we would add a button to Upload Custom Palette
  

• A model would appear that directs users to upload. This is left blank because we need to discuss how this actually plays out, is it a link, some file on desktop? What restrictions exists? The modal represents a space where we need to guide the users to upload what we can display.
  

• Now that users have added a custom palette, a color category for custom allows then to select that in the future across catalogs.