location-importer.in: process unaligned IP ranges in RIR data files correctly

location-importer.in: process unaligned IP ranges in RIR data files correctly

The IP range given in an inetnum object apparently not necessarily
matches distinct subnet boundaries. As a result, the current attempt to
calculate its CIDR mask resulted in faulty subnets not covering the
entire IP range.

This patch leaves the task of enumerating subnets to the ipaddress
module itself, which handles things much more robust. Since the output
may contain of several subnets, a list for the inetnum key is necessary
as well as a loop over them when conducting the SQL statements.

Fixes: #12595
Cc: Michael Tremer <michael.tremer@ipfire.org>
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>