Export entries result into a geojson or a live leaflet map

Previously we will need this: #135

I believe this feature could be a "killer feature" of LiberaForms making it able to also export its entries into a leaflet map (with clickable points showing a description formatted from the other entries) (initially the popup description could just be a simple list of "Title of question: Answer
").

For those forms that would have a coordinates input type field, the liberaforms would allow .geojson export file or, live .geojson url (that can be imported from other apps like https://umap.openstreetmap.fr/ , etc).

This would allow the creation of collectable map info repositories(the ones that normally require complex webapps, wordpress plugins, etc...) with a simple form creation. It could really help the crowdsourcing needs of many movements, projects and communities.