Macro impl_case_insensitive_enum

macro_rules! impl_case_insensitive_enum {
    ($enum_name:ident, { $($variant_str:expr => $variant:ident),* $(,)? }) => { ... };
}

Macro to implement case-insensitive deserialization for enums with simple string variants.

This macro generates a custom Deserialize implementation for an enum that makes variant string matching case-insensitive. It works with enums that use string representation in serialization (e.g., with #[serde(tag = "type")]).

The generated implementation will match variant names case-insensitively, so both "variant1" and "VARIANT1" will be deserialized as MyEnum::Variant1.