* This patch also adds handling for iterators in the sanitizing
function for YAQL results. JSON serialization for iterators now
works correctly but the issue is that they can be used only once.
So, for example, if we got a result from YAQL and performed JSON
serialization for it, then the iterator is already empty and
the data structure is just corrupted. So we can't further pass
to executors and other subsystems. The solution is just to sanitize
iterators after they're just returned from YAQL.
* Added a test to make sure that action input reaches an executor
not corrupted, although it gets saved into DB and hence serialized
into JSON.
* Changed the Sphinx entry in requirements.txt so that the version
3.0.0 is now excluded (it breaks the build).
Closes-Bug: #1871567
Change-Id: I47abe0904b49d72e33eb10080c71fb81980d44da