Add a static image on Index to the `location` field

[adrianthedev]

Feature

It would be nice to use https://github.com/ankane/mapkick-static to generate static images for the Index view.
We could initially show a small thumbnail and on hover (we use tippy.js) show a bigger version.

Approach

• create the Avo::Fields::LocationField::IndexComponent to render the static image
• remove the hide_on :index from LocationField
• use https://github.com/ankane/mapkick-static to render the image