Fix build issues with AWS models, and remove enum types

[mullermp]

When building the AWS models, there were some issues with the generated code. This PR includes a few various fixes:

1. (possibly temporary) Remove the enum type definitions - they cause issues because of reserved words. Some enums are named as "END" which is a ruby keyword.
2. Use root namespaces for ::Smithy because there is a shape called Smithy in a service model.
3. Fix paginator inheritance generation - merge the traits then check if the merged trait is empty. Added test cases for this.
4. Use location name camelcased for union type generation - it was not correct using the camel case of the already snake cased name because of acryonyms. (example: graphQL should be :graph_ql and GraphQL and not :graph_ql and GraphQl.