Strip common prefix from enum variants

[rkr35]

Here's what a generated enum looks like:

#[repr(u8)]
pub enum EInterpCurveMode {
    CIM_Linear,
    CIM_CurveAuto,
    CIM_Constant,
    CIM_CurveUser,
    CIM_CurveBreak,
    CIM_CurveAutoClamped,
    CIM_MAX,
}

Since the variants of a Rust enum do not pollute the namespace that contains the enum, there is no need to prepend a common prefix to each enum variant. We should also normalize variant names so they are always PascalCase.

Here's how we should generate the above enum:

#[repr(u8)]
pub enum EInterpCurveMode {
    Linear,
    CurveAuto,
    Constant,
    CurveUser,
    CurveBreak,
    CurveAutoClamped,
    Max,
}