feat - pipeline plugins

[JarbasAl]

a new plugin class should be added to OPM, decoupling the pipeline stage implementations from ovos-core

#349

companion work:

• turn adapt into a pipeline plugin https://github.com/OpenVoiceOS/ovos-intent-plugin-adapt
• turn padatious into a pipeline plugin https://github.com/OpenVoiceOS/ovos-intent-plugin-padatious -> allows ditching padatious dependency from ovos-core for good
• turn padacioso into a pipeline plugin feat/pipeline_plugin padacioso#20
• import old services from the new packages for compat + mark old imports for deprecation in 0.2.0

unblocks:

• OOVSkills proposal: OOVSkills #273
• OCP pipeline plugin
• jurebes pipeline plugin feat/jurebes #310
• persona pipeline plugin feat/persona pipeline #370
• CommonIOT pipeline plugin