Add option to fail packaging if submodules were not cloned

[ssbarnea]

If someone has a project repository that uses submodules which are part of the packaging, running setuptools on a clone without recurse will produce a broken/incomplete package.

The user will not know what caused the issue until is too late.

On ansible-lint we got this reported as https://github.com/ansible/ansible-lint/issues/3424 where user complained that he cannot run the tests AFTER installing the package. The funny bit is that the installation does not fail, making him believe he has the package installed. In fact, he installed only some bits of the package.

In order to prevent similar accidents, I think we should have a flag that would require a full recursive clone before doing the packaging. I am mentioning this as an opt-in because I suspect that not everyone wants to force the cloning of submodules before packaging, so this approach will be less risky.