create Spatialite metadata in one trans if possible

Spatialite 4.1.0 supports an argument to InitSpatialMetaData() to create
all the metadata within one transaction to speed up the operation
significantly on some systems. ticket #23152
I think it'd be better to have a property something like `supports_spatialite_initialization_with_transactions` on the `DatabaseFeatures` class: https://github.com/django/django/blob/695956376ff09b0d6fd5c438f912b9eb05459145/django/contrib/gis/db/backends/spatialite/base.py#L18-L21.