Refactored GIS-related JavaScript initialization to eliminate inline
scripts from templates. Added support for specifying a base layer using
the new `base_layer_name` attribute on `BaseGeometryWidget`, allowing
custom map tile providers via user-defined JavaScript.
As a result, the `gis/openlayers-osm.html` template was removed.
Thanks Sarah Boyce for reviews.
Co-authored-by: Natalia <124304+nessita@users.noreply.github.com>