Use custom ASN if defined in inventory

Should be defined in partner's general.yaml file, e.g. partner: LHCONE: asn: 22442

Used in:

• bgp_config
• policy_options (block community).

assigned to @Aleksandr.Kurbatov

enabled an automatic merge when all merge checks for 6d2140ef pass

merged

mentioned in commit 5ef30b14