Improvment/parsers: usage of dynamic plugin instead of hardcoded ones

[AlteredCoder]

Is your feature request related to a problem? Please describe. I used the source feature of parsers that can download needed data for the parser, but even if the parser geoip-enrich is not installed, crowdsec try to load it.

Describe the solution you'd like A dynamic plugin system that will load plugin only if their parser are installed..