Delegate method assist on enums

Imo, the assist should work on enum variant fields, if all variants have the same named field or a field at the same index if they are tuple variants and all of the fields share a method. Having wrapper enums that "unify" two distinct types that serve similar purposes does happen at times.

enum Enum {
    V1(Type$0),
    V2(Type2),
}

here we should offer the assist to delegate any methods shared by Type and Type2 and then generate a method that matches on the variants and delegates appropriately.

Start by locating the delegate-method assist entry point and any tests covering enum or variant-field delegation. Compare the requested behavior for named and tuple fields, then consider the work complete when shared methods are offered and generated delegation matches each enum variant.