Add config to enum to make it lowerCase

It would be good to have configuration in order to change casing for enum values disregarding what tech stack i use.
e.g. for NodeJs it is nice to have enum upercased (having in minde that TypeScript users got used to use i tlike this from C#), but dor Dart best code practice is camelCassing. If re in mongodb camelCased enum values as weel as in dart code - I am forced to have same in NodeJs.

The issue names no files, tests, or entry points. Start by locating enum generation and configuration handling in the TypeScript GraphQL schema code, then check how enum values are currently emitted. Done means a configuration can control enum casing independently of the consuming language, with tests covering the requested casing behavior.

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