Demo/Test processor returning multiple outputs

[francescoingv]

Here is a demo processor extended_output_only.py returning the following outputs (no input is needed) for:

• a boolean (json/text)
• a number (json/text)
• a string (json/text)
• a binary (TIFF file) (binary)
• an array of binary (json)
• an object containing a string and a binary (json)

I tested it against some payloads, using default response ("response": "raw"), and here is the report I produced report_ExtendedEchoProcessor_7_7_26.odt

Unless I made something wrong in the code (which is quite possible), there are some aspect to consider as not working as expected.

I think it may help testing also for "response": "document" (see issue #2305),
or may require amendments to handle also that aspect.
I did not try for "response": "document", as I am not sure the outcome I should expect.

It could be used to work on solving issue #2255.

It is a followup to issue #2313.