conf: parser: add Mikrotik firewall parsers

[hlein]

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[hlein]

Gathered some sample logs, ran them through fluent-bit w/these parsers, compared number of input lines to number of output lines (i.e. matched lines).

$ for A in firewall proxy dhcp ovpn logins other ; do wc -l mikrotik_${A}.numbered && cat mikrotik_${A}.numbered | fluent-bit -q -R parsers_mikrotik.yaml -i stdin -p parser=mikrotik-${A} -o stdout -p format=json_lines | jq -r '.log_seq' | sort -n > matched_${A}.txt ; wc -l matched_${A}.txt ; done
firewall
620784060 mikrotik_firewall.numbered
620784060 matched_firewall.txt
proxy
132515 mikrotik_proxy.numbered
132515 matched_proxy.txt
dhcp
860 mikrotik_dhcp.numbered
860 matched_dhcp.txt
ovpn
3794 mikrotik_ovpn.numbered
3794 matched_ovpn.txt
logins
8 mikrotik_logins.numbered
8 matched_logins.txt
other
2003 mikrotik_other.numbered
2003 matched_other.txt

[hlein]

Simplified this since it is separate from other changes. Ready to be a PR against upstream.