Transform current output formats to postprocessing

[andurin]

The pySigma (>=0.10.0) post-processing feature allows a much more dynamic way to create different output formats.

ES Backend should be rewritten including the current output formats as templates.

[Lucaazel]

Does this mean we can have many detection types (other types than query), such as new_terms or threshold?

[thomaspatzke]

It depends what detection type means. If it embeds a Lucene or EQL query that is already generated by the backend then this is possible. If that are independent query languages then they have to be implemented as custom backend.