Feature request: Automatically change projection depending on what background layer you choose ? Limit zoomout to projection or background layer extent ?

**Is your feature request related to a problem? Please describe.**
We have a few WMS background layers in our application, added in config-viewer.xml,
we also have a background layer for a different region of the world which requires a different projection for the background layer to be displayed properly. Users changing the map and having to select the correct projection manually with the user-interface is abit of a hassle. Maybe one could define the Coordinate Reference System inside ows-context:layer in config-viewer.xml and then geonetwork knows it should automatically switch to that given projection.

Another nice feature would be to limit zoomout to background layer extent (Constrained Extent), at the moment it's limited to the world. But if one's background layer is just of a country, a user can by mistake zoom out of bounds and never find their way back again to the map

I have no idea how to set this in geonetwork

Start by tracing how config-viewer.xml defines ows-context:layer entries and how the map viewer applies the selected background layer. Determine where projection changes and zoom constraints are handled, then define acceptance checks for automatic CRS switching and preventing zoomout beyond the background extent.

Written by the indexing model from the issue text.