Support coloring vector features by an attribute containing a hex color code

[mfisher87]

Resolves #651

Description

This render type uses a hex code in a vector feature's attribute to define each feature's color.

For example, this undersea cables dataset includes a bunch of lines, each containing a color attribute which has a hex color code value.

The new render type allows selecting from attributes with values that look like hex color codes, and using the color from that attribute to color the feature.

Checklist

• PR has a descriptive title and content.
• PR description contains references to any issues the PR resolves, e.g. Resolves #XXX.
• PR has one of the labels: documentation, bug, enhancement, feature, maintenance
• Checks are passing.
  Failing lint checks can be resolved with:
  • pre-commit run --all-files
  • jlpm run lint

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📚 Documentation preview: https://jupytergis--713.org.readthedocs.build/en/713/
💡 JupyterLite preview: https://jupytergis--713.org.readthedocs.build/en/713/lite

[github-actions]

👈 Launch a Binder on branch mfisher87/jupytergis/canonical-vector-color

[github-actions]

Integration tests report: appsharing.space

[mfisher87]

Is "canonical" a good name for this render type? I kind of hate it... maybe "Direct"? Other ideas?

[arjxn-py]

Thanks for starting this Matt :)

Looks like this is still a WIP? does it work for any example?

For me it fails with:

canonical.mp4

[mfisher87]

@arjxn-py Thanks for the review! Please try the undersea cables dataset listed in the PR description! That one contains a color attribute with hex codes.

[mfisher87]

While I was in there, I also added checks for "graduated" and "categorized" render types; both require numeric values right now. In the future, we want to support non-numeric fields to be displayed with categorical rendering: #654

I also feel that we need to DRY and simplify this logic a little bit: #717

addressed!

[arjxn-py]

Looks Good!
Works Well, Thanks :)