RFC5424Log structured data

[mmitucha]

Added structured data part for rfc5424 log type according to https://datatracker.ietf.org/doc/html/rfc5424

Sample rfc5424 log:

<125>1 2022-03-16T17:00:56.983Z seniorpartnerships.net aut 5073 ID698 [exampleSDID@353664 iut="8" eventSource="Application" eventID="306249"][examplePriority@97903 class="high" method="POST" uri="/granular/sexy/integrate" status_code="504" time_millis="186" remote_host="128.200.83.221" remote_ip_addr="156.235.138.200"] If we back up the interface, we can get to the JBOD capacitor through the neural XML bus!

the structured data [exampleSDID@353664 iut="8" eventSource="Application" eventID="306249"][examplePriority@97903 class="high" method="POST" uri="/granular/sexy/integrate" status_code="504" time_millis="186" remote_host="128.200.83.221" remote_ip_addr="156.235.138.200"] consist of two parts inside square brackets([...][...]), which is valid and I think it is good for testing rfc5424 parser.