Fix several AH meter issues

[axelstudios]

What's this PR do?

• Adds missing AH restrictions to all meter reading endpoints
• Adds AH tests for all meter reading endpoints
• Removes meter reading PATCH endpoint for consistency
• Fixes all writable PropertyView endpoints to restrict actions to members or higher, and include organization_id
• Fixes all meters Swagger endpoints to include organization_id
• Query reduction in MeterReadingViewSet
• Adds a datetime Swagger schema helper

How should this be manually tested?

Tests should pass