Add all the latest from the Felt REST API

[binaryseed]

This PR updates the felt_python library with all the latest capabilities from the Felt REST API

• Includes notebooks that walk through examples of using the new functions
• Includes tests that cover most of the functionality
• Sets up CI to run the tests

Also closes #21

[arredond]

Love the direction of this! Keeping the library up to date with the Felt API and adding tests is really invaluable. Left some small notes (mostly nits).

[arredond]

Is "show" the right term here? This still returns a list, it doesn't print anything. The developer docs also say "list" so we should keep these consistent

[binaryseed]

Yeah, show isn't correct here. To match all the other endpoint functions, this would be get_element_group.

The old list_elements_in_group makes sense when you read it, but doesn't follow the naming pattern. For example, we have get_layer_group not list_layers_in_group.

Also it technically returns a GeoJSON object, not a literal list.

I'll change it to get_element_group for now and we can consider if we should keep that or just stick with the old function.