pfSense

Replace more problematic multilevel config array access

Fix text_to_compressed_ipv6() to omit %ifname from v6 addresses

Prior to this, v6 addresses would be considered by Net_IPv6::compress() to have
an ipv4 part consisting of all text from the address from the final colon
separator, and try to treat it as such. This is now problematic in php 8 as when...

Use config_path_enabled() and config_get_path() for troublesome paths

Add config_path_enabled() function and associated tests

Replace more direct config array access with config_get_path()

Change numerous direct references into config to config_get_path()

Correct dhcpv6 enable check to use config_get_path()

Use config_get_path for openvpn interfaces and ifgroups

Use config_get_path for looking up static ARP entries

Use config_get_path() for friendly ifnames and vlan configs

These elements may not exist in the config depending on the user config and
available ifaces, causing errors in php 8 when attempting to do element access
on a string or nil value.