add GeoJSON Layer Display

I propose for Plotly the ability to overlay multiple GeoJSON objects on a map, each with a distinct color and corresponding legend, without the need to bind them to a specific data attribute (like z in choropleth maps).

Currently, Plotly.js requires GeoJSON features to be associated with data for visualization. However, there are use cases, including one of my own, where the goal is simply to display the shapes defined by GeoJSON files, differentiate them with colors, and provide a legend for reference. This is purely for visual comparison and spatial representation.

For example, I have two GeoJSON datasets representing which type of agricultural simulation performed better for a region: Yield Potential (in blue) and Rainfed Potential (in yellow). I want to display these on a map, each with a random but consistent color, and include a legend to identify them. See this example image for reference.

Implementing this feature would benefit users who need to visualize spatial data layers without additional data-driven coloring. It would enhance Plotly's functionality and maintain consistency within applications that rely on Plotly for other types of data visualization.

I am open to trying contributing to the development of this feature and would like to hear the community's and maintainers' thoughts on its potential inclusion in Plotly.js.

Start by examining Plotly.js map and choropleth support, especially how GeoJSON features are currently associated with data. Define the scope for displaying multiple GeoJSON layers with distinct colors and legend entries without a z attribute. The issue provides no file or test locations, so the relevant entry points and acceptance tests will need to be identified.