[ObjC][Gen] Emit ObjC strings to respective sections (#84300)
Clang emits ObjC strings into special sections
https://github.com/llvm/llvm-project/blob/d5e7c27d53887e6ae490d8e26193a54987728458/clang/lib/CodeGen/CGObjCMac.cpp#L4056-L4072
As far as I can tell from `CGObjCMac.cpp`:
* types go into `__objc_methtype`
* class, category, and protocol names go into `__objc_classname`
* method names, property names, and property types go into
`__objc_methname`
See also https://github.com/swiftlang/swift/pull/84236.
