Add add & remove node commands to zwave_js websocket api

[cgarwood]

Proposed change

This adds websocket commands to add and remove Z-Wave nodes for the Z-Wave JS integration.

Still need to write tests.

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

• Frontend PR: Add wizards for adding and removing Z-Wave JS nodes frontend#8174

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][dev-checklist]
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

[MartinHjelmare]

Looks good! I'll have another look when tests are pushed.

[cgarwood]

Pushed up most tests, still have a few more bits of the remove_node function to cover with tests but wanted to make sure these were on the right track.

[MartinHjelmare]

We need to rebase too.

[MartinHjelmare]

Great!