ids-functions.pl: Introduce extraceruleset() function.

ids-functions.pl: Introduce extraceruleset() function.

This function is used to extract the required config and rules files
from the stored rules tarball for a given ruleset provider.

* The files will be extracted to a temporary directory layout in
  "/tmp/ids_tmp".

* Names of config files will be adjusted in case multiple providers
  offers the same config files, which is very common.

* The name of the single rulefiles will be adjusted to start with
  the vendors name to allow assigning them very easily to a single
  ruleset provider.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>