Enable selection of background maps to include in the map selector

[naomap]

Is your feature request related to a problem? Please describe. The background map selector offers a choice of 10 styles that are all based on OSM and are fairly similar.
As a map producer, I want to choose the background maps that are made available to my map readers. Depending on the purpose of the map and the covered area, I may choose a selection of background maps such as hiking maps, aerial imagery, a custom map, and so on. The map reader is then offered a limited list of adequate background maps.

Describe the solution you'd like When configuring the map, enable checking (with a checkbox) the background maps I want to include in the background map selector. Even better, have a Drag and Drop mechanism that enables me to select and order the maps so that they are presented in a precise order – the first map is then the default background map displayed when opening the map.