[Maps] update map.tilemap.url to support arrays

[jarmovanlenthe]

Describe the feature:
In kibana.yml, you can provide your own tilemap url (map.tilemap.url). However, you can only provide one. The option map.regionmap.layers is an array. It would be desirable to be able to provide multiple tilemap URLs as well.

Describe a specific use case for the feature:
When you have multiple tilemaps hosted, you want to be able to provide choice to users, without having them to provide the URLs themselves.

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)

[thomasneirynck]

@jarmovanlenthe note that in the Maps-app you can add any number of tile-layers to a Map, and you do not need to configure these up front in the kibana.yml.

Does this work for you?

Or do you want to pre-configure a number of tile-layers so your users can just pick&choose from a list?

[jarmovanlenthe]

The latter. Would be good to be able to configure multiple layers beforehand so that users do not need to config (and thus, know all the different URLs) those themselves.

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[nreese]

In order to provide better transparency of priorities, issues that will not be prioritized within the next 24 months are being closed.

Tracking request in Maps ice box #154870