Allow lower-case DU cases when [<RequireQualifiedAccess>] is specified
Currently, it is not allowed to declare DU cases with lower-case letters. For instance, this is not allowed:
type Foo =
This yields: error FS0053: Discriminated union cases and exception labels must be uppercase identifiers
As I understand it, this is to prevent ambiguity in pattern matching between matching a union case and binding to an identifier. However, this is not an issue if the [<RequireQualifiedAccess>] attribute is specified on the DU. Therefore, I propose we allow lower-case cases in this case.