Add support for new feeds to Dataplane parser

[monoidic]

This PR adds support for all of the currently available Dataplane feeds, i.e dns{rd{,any},version}, proto41, smtp{data,greet}, telnetlogin and vncrfb, in addition to the ones currently supported.
Some general code changes to the parser were also made.
Tests for the newly supported feeds were also added, along with a rework of the tests.

[codecov-commenter]

Codecov Report

Merging #2102 (e14ec34) into develop (5328544) will decrease coverage by 0.00%.
The diff coverage is 90.56%.

@@             Coverage Diff             @@
##           develop    #2102      +/-   ##
===========================================
- Coverage    76.04%   76.04%   -0.01%     
===========================================
  Files          434      434              
  Lines        23218    23222       +4     
  Branches      3104     3108       +4     
===========================================
+ Hits         17657    17660       +3     
- Misses        4852     4853       +1     
  Partials       709      709              

Impacted Files	Coverage Δ
intelmq/bin/intelmqctl.py	9.32% <0.00%> (-0.02%)	⬇️
intelmq/bots/collectors/http/collector_http.py	59.61% <ø> (ø)
...elmq/bots/collectors/http/collector_http_stream.py	40.00% <ø> (ø)
intelmq/bots/collectors/misp/collector.py	41.86% <ø> (ø)
...s/collectors/shadowserver/collector_reports_api.py	89.28% <ø> (ø)
intelmq/bots/experts/http/expert_status.py	80.00% <ø> (ø)
intelmq/bots/experts/jinja/expert.py	39.39% <ø> (ø)
intelmq/bots/experts/splunk_saved_search/expert.py	20.75% <ø> (ø)
intelmq/bots/experts/tuency/expert.py	86.00% <ø> (ø)
intelmq/bots/outputs/elasticsearch/output.py	78.04% <ø> (ø)
... and 14 more

[ghost]

I would appreciate entries in intelmq/etc/feeds.yaml :)

Apart from that I found nothing to complain about ;)

[monoidic]

I added the documentation, plus a helper function called _convert_datetime to ensure extra.first_seen is converted to IntelMQ DateTime.

[ghost]

Thank you!