* updated builtin extension to parse region directly from ARN
- added a unit test
- added some comments/light refactoring
* updated golden files with proper ARNs
- ARNs need to be right format now that they are being processed
* updated tests and integration tests
- removed 'region' from all EnvoyExtension arguments
- added properly formatted ARN which includes the same region found in the removed "Region" field: 'us-east-1'
782aaee69a