Adds backend support for an "automatic updates" setting at the workspace scope.

Automatic updates causes workspaces to attempt to automatically update to the latest template version when they are auto-started.

However, this is only possible if the workspace's present template, and the updated template have "compatible" parameters. This means that each parameter of the updated template must either

1. Have a parameter of the same name and type from the old template
2. Be mutable and have a default value

Any new parameter in the new template that is immutable or does not have a default value will cause the auto-start to fail. The user must manually upgrade the workspace, providing the new immutable or required parameters.

This issue covers adding the setting to the database, plumbing it to workspace APIs, and modifying the auto-start behavior as described above.