Explore Plugin based system for Flavor processors

[DiegoPino]

What is this?

I waited too long for this so time to make a first branch to complement the good work of @giancarlobi
The idea here is that each post processor is derived from a Plugin. Plugins can/should be able to be connected to each other and have different inputs and outputs. They have settings and can self sustain complex work.

Depending on the number of assets/complexity of the task and where/how something is running they can be enqueued and run sequentially like @giancarlobi demo scripts or could, eventually run via a UI facing batch (need to figure out the exact conditional for this).

The branch associated with this issue will be mostly for now an experiment and should serve as starting ground for generalizing the needed functionality. Goal is to have HOCR as full implementation in the next 14 days. Beta3 will have this working and enabled.

[DiegoPino]

Implemented (since 2020 👁️ )