Does not mock with autodoc_mock_imports

Sphinx autodoc uses `autodoc_mock_imports` to, well, mock imports.

Trying to mock modules with `MagicMock` causes them to be excluded from the compiled docs, see https://github.com/sphinx-doc/sphinx/issues/4956

Since automodapi doesn't respect `autodoc_mock_imports`, it tries to import the modules, but since they can't be mocked otherwise (as far as I have been able to get) this breaks automodapi when modules need to be mocked (ie. build with readthedocs).

Start by reproducing the documentation build using Sphinx's autodoc_mock_imports with a MagicMock-imported module, then inspect how automodapi discovers and imports modules. Compare the generated output with and without mocked imports; done means automodapi respects autodoc_mock_imports without excluding the mocked modules from the compiled docs.

Written by the indexing model from the issue text.