Allow users to suppress autodoc.mocked_object warnings

[CyrilRoelandteNovance]

No description provided.

[tk0miya]

I don't understand why you'd like to suppress these warnings. I think Sphinx generates broken (unexpected) document if they are emitted. Is there any reason to ignore such a situation? I need to know the real case you're facing.

[CyrilRoelandteNovance]

In https://github.com/openstack/glance_store , going from Sphinx 4.1.0 to 4.2.0 breaks the documentation build:

(docs)cyril@debian:~/openstack/glance_store$ sphinx-build -W -b html doc/source doc/build/html
...
Warning, treated as error:
A mocked object is detected: 'glance_store.common.cinder_utils'

We do mock glance_store.common.cinder_utils.

Someone mentioned that this commit could be a fix, but I tried using the 4.x branch and got the same error:

(docs) cyril@debian:~/openstack/glance_store$ pip install git+https://github.com/sphinx-doc/[email protected]
...
(docs) cyril@debian:~/openstack/glance_store$ pip list | grep Sphinx
Sphinx                        4.3.0.dev20211103
(docs)cyril@debian:~/openstack/glance_store$ sphinx-build -W -b html doc/source doc/build/html
...
Warning, treated as error:
A mocked object is detected: 'glance_store.common.cinder_utils'

Are we doing someting wrong?

[AA-Turner]

This PR seems harmless, happy to merge.

A