Call read_hats for spatial filters on unaltered catalogs

[camposandro]

Users often perform spatial filters after a read_hats call where the search_filter was not specified.

E.g. this:

# path 1
cat = lsdb.read_hats(...)
cat = cat.cone_search(...)

instead of:

# path 2
from lsdb.core.search import ConeSearch
cat = lsdb.read_hats(..., search_filter=ConeSearch(...))

If the user goes for "path 1" we should call read_hats again (on behalf of the user), to apply the search filter as in "path 2". We should do this on Catalog.search and only if the catalog is UNALTERED. We cannot forget to pass the remaining args and kwargs used on the user's initial read_hats call.

[camposandro]

We currently set the total_rows of a catalog to zero on the _create_updated_dataset method. Checking if the total rows is greater than zero could be enough to check if the catalog is unaltered.