This is the 2nd part to
https://github.com/llvm/llvm-project/pull/124752. Here we make sure to
set the `DICompositeType` `EnumKind` if the enum was declared with
`__attribute__((enum_extensibility(...)))`. In DWARF this will be
rendered as `DW_AT_APPLE_enum_kind` and will be used by LLDB when
creating `clang::EnumDecl`s from debug-info.
Depends on https://github.com/llvm/llvm-project/pull/126044
