Update vpn.pm to add IPSec Tunnel Counter

[jummo]

Add counter for IPSec tunnels and remove default to CRITICAL if one tunnel is down.

Community contributors

Description

Reopen #5341 as I have closed it by accident

Add a counter for IPSec tunnels on Fortigate firewalls.
With this counter it is possible to check the current available IPSec tunnels and set the status to WARNING or CRITICAL on the count.

Added to the output IPSec tunnels state up: 2 in the global sections.
Full output:
OK: Virtual domain 'root' Logged users: 0, Active web sessions: 0, Active tunnels: 0, IPSec tunnels state up: 2 - All vpn are ok | 'root#vpn.users.logged.count'=0users;;;0; 'root#vpn.websessions.active.count'=0sessions;;;0; 'root#vpn.tunnels.active.count'=0tunnels;;;0; 'root#vpn.ipsec.tunnels.state.count'=2tunnels;@1:1;@0:0;0; 'root~t_hub1-1_111#vpn.traffic.in.bitspersecond'=1077.27b/s;;;0; 'root~t_hub1-1_111#vpn.traffic.out.bitspersecond'=1206.72b/s;;;0; 'root~t_hub2-1_111#vpn.traffic.in.bitspersecond'=1076.06b/s;;;0; 'root~t_hub2-1_111#vpn.traffic.out.bitspersecond'=1205.12b/s;;;0;

Type of change

• Patch fixing an issue (non-breaking change)
• New functionality (non-breaking change)
• Functionality enhancement or optimization (non-breaking change)
• Breaking change (patch or feature) that might cause side effects breaking part of the Software

How this pull request can be tested ?

Run
`
perl src/centreon_plugins.pl --plugin=network::fortinet::fortigate::snmp::plugin
--mode vpn
--hostname firewall-cluster.example.com
--snmp-version 3
--snmp-username='SNMP-User1'
--authpassphrase='secret1'
--authprotocol='SHA'
--privpassphrase='secret2'
--privprotocol='AES'
--warning-ipsec_tunnels_count='@1:1'
--critical-ipsec_tunnels_count='@0:0'
--use-new-perfdata
--filter-vpn='_11'

Debug information

I have run with --debug option and attached the snmp data from it.
debug.run.snmp.data.txt

Attached are also the MIB files from Fortigate and and extract of the used one with PRTG MIB-Browser.
Fortigate.MIBs.zip

Checklist

• I have followed the coding style guidelines provided by Centreon
• I have commented my code, especially hard-to-understand areas of the PR.
• I have rebased my development branch on the base branch (develop).
• I have provide data or shown output displaying the result of this code in the plugin area concerned.