Custom label for code-block captions (Output 1.2 / Input 1.2 / Source 1.4 / Directory tree 1.2 / etc)

[jonascj]

Is your feature request related to a problem? Please describe.
Although Listing 1.2 is used in English literature for both source code listing, pseudocode, programoutput, console sessions etc. I would often prefer to use "Output 1.2" when listing output, "Source 1.2" when listing source code etc.

I refer to the Listing in Listing 1.2 as the caption label. This might be the wrong terminology, I don't know. It is of course not to be confused with labels used with references.

Describe the solution you'd like
Input:

.. code-block::
  :caption: Output of nested loop.
  :caption-label: Output

  $ python -V
  Python 3.7.4

Output: Output 1.2: Output of nested loop.

Although not the prettiest, the code-block counters could be kept as they were, i.e. no matter the :caption-label: they would use the same counter producing what is in the screenshot.
I suppose the optimal thing would be to use separate counters for each :caption-label:.

Describe alternatives you've considered
I suppose one could use / create special extensions for each use case, extensions which would provide new directives like .. output-block::. This would be semantically pretty, but also a bit overkill in my view, after all it is just a label for the caption, it is not like the block itself should be rendered differently.