vyos_net_name: T6544: Updated the vyos_net_name script

Improvements in the vyos_net_name:

• Used a new locking system, to be sure that multiple running scripts will not

try to perform operations at the same time.

• Replace logging from a file to syslog. This is common with all the rest logs,

and additionally gives a better view of actions done during a boot.

• Small bug fix in get_configfile_interfaces(): exit with an error in case a

config file cannot be parsed. This resolves potentially an unbound config object.

• Minor formatting fixes to follow our requirements.