Map should be keyboard navigable

[mgifford]

CKAN version
https://demo.ckan.org/dataset/sample-dataset-1/resource/ecd4a62d-998b-46e4-8a64-cadac2125c64

Describe the bug
There is no reason that you should need to be able to use a mouse to navigate this map.

You can navigate to the button with the tab key, but then can't activate it.

The arrow keys left/right work but not up/down.

Steps to reproduce

• Navigate to the URL above.
• Without using your mouse or touchpad, using the tab key, navigate to the map.
• try to zoom in/out into the map

Expected behavior
You should be able to use the button to zoom in & out. It would also be useful if this were tested with voice control devices. Not every can use a mouse.

Additional details
https://webaim.org/techniques/keyboard/