Add hetzner as cloud provider

[fkantelberg]

What does this PR do?

This PR adds the Hetzner GmbH cloud as cloud provider to salt-cloud. It wraps around the hcloud package provided by Hetzner GmbH.

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltstack.com/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

No

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See GitHub's page on GPG signing for more information about signing commits with GPG.

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[Ch3LL]

This requires test coverage for all of the new functionality and a changelog entry. Since we do not have access to the hetzner cloud, unit tests will be the best approach for now.

[fkantelberg]

@Ch3LL Thank you. As requested I added the unittests and the changelog entry.

But I have no idea why the debian9 pytest is failing. Is this related to my changed when I see problems in FAILED tests/integration/modules/test_state.py::StateModuleTest::test_requisites_onfail_all?

[Ch3LL]

We try to stray away from these module level variables as they can cause headache in the future and hard to find if anyone ever ends up importing this test module.

Also another ask, we have recently migrated to pytest. Would you mind migrating this test to tests/pytests/unit/cloud/. You will need to create the cloud directory since there isn't currently one there. thanks :)

[Ch3LL]

You should be able to ignore that test failure. I am re-running it to see if it fails again

[fkantelberg]

I migrated the tests to pytest and fixed the mentioned comments and all unittests seem to be green now.

[Ch3LL]

Thanks!

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Congratulations on your first PR being merged! 🎉