Graceful fallback if translations for device automations are missing

[emontnemery]

Proposed change

Fall back in case device automation translations are missing.
If translation for subtype is missing, use subtype as is.
If translation for type is missing generate string "subtype" type.

Type of change

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

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• 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