Add better support for panelizer_entity container

This patch adds support for the panelizer_entity container.

For reference:

Before:

After:

Thank goodness for test coverage. Let's try that again...

Well let's try that again...

And one more with an updated test.

Now that we have better test coverage, this should get covered by that.

This is the test only. This should fail.

This is the test and the patch. This should pass.

Whoops. Let's try this again.

Still having issues. Trying to see if it's a CI issue, or an issue with my patch.

Trying a slight modification to the setup() function to see if it can resolve properly.

So I'm guessing the reason this keeps failing to run is due to panelizer being an external module, instead of a submodule of panels. Since panelizer was never specified as a dependency in the .info file (mainly as I wanted to keep this optional), I don't believe it's actually downloading the code. I'll test this theory later, but jotting it down now in case anyone stumbles across this thread.

Just uploading this to test if adding the dependency fixes the test issue. I don't necessarily want to add this module dependency, but I just want to confirm if it solves the bug in the CI environment.

Not sure why it didn't queue for testing. Trying again.

Just saw the note about `test_dependencies[]` in the info file. Giving that a shot.

Attempting to use `package:module` declarations in info file

Now that the test issue has been resolved, I'm gonna focus on rewriting the tests in the same manner I'm looking to rewrite the other tests so, still needs work.

Just realized I never attributed credit here for the help. My bad.