Add push and build for layered deployments

[EliiseS]

iotedgedev Pull Request Checklist

• Versions updated (both init.py files, CHANGELOG, setup.py, setup.cfg)
• Unit tests pass locally
• Quickstart steps locally validated
• Passes unit tests in CICD pipeline (green on Github pipeline)
• Pypi RC version passes Edge CICD pipeline validation for cross-tool validation

Additional comments

Part of #430, but not the full solution. (Don't close the issue with this PR)

This PR covers:

• Adding ability to create config files from layered deployment templates.
• Push and build images from layered deployment templates.
• Minor fixes to the dev environment (linting, small refactoring)
• Pin all python versions to prevent New resolver downloads hundreds of different package versions, without giving reason pypa/pip#9215
• Fix issues with tests generating non git ignored code and not cleaning up after themselves

Layered deployment template reference: https://github.com/MicrosoftDocs/azure-docs/blob/master/articles/iot-edge/how-to-deploy-cli-at-scale.md#configure-a-deployment-manifest

Layered deployment with no modules: Azure/iotedge#5299

[marianan]

LAYERED_RUNTIME_TAG

Should this be a boolean flag instead of integer version? Also, I would assume the default value should be false? #Resolved

[EliiseS]

I've changed my mind three times on what to do with this and I've landed on that I've removed this completely and just determine if it's a layered deployment schema by looking for the content key in the top level.

This allows this PR to be as self standing as it can be, since the idea I have for this is to just enable creating config from layered deployment templates and build/push those any images.

[marianan]

🕐

[marianan]