Block custom integrations with missing or invalid version

[ludeeus]

Breaking change

As mentioned in every release since 2021.3, custom integrations will require a version key in their manifest file.
If that key is missing, the custom integration will no longer be loaded.

For more details see https://developers.home-assistant.io/blog/2021/01/29/custom-integration-changes#versions

Proposed change

The last part of the plan outlined in https://developers.home-assistant.io/blog/2021/01/29/custom-integration-changes#versions. With this custom integrations that are missing the version key, or have an invalid version key will no longer be loaded.

That also means that legacy integrations will not load with this, since those do not have a manifest file.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[alandtse]

LGTM. Shouldn't there be a doc PR to identify the fact it's no longer a future requirement?

[ludeeus]

The documentation always stated that it's required https://developers.home-assistant.io/docs/creating_integration_manifest#version

EDIT: The blog post stated it was a future version home-assistant/developers.home-assistant#912