os2: better copy_directory, and add native copy_file and copy_directory variants on MacOS

core/os/os2/dir_posix_darwin.odin

@@ -0,0 +1,17 @@
+#+private
+package os2
+
+import "core:sys/darwin"
+
+_copy_directory_all_native :: proc(dst, src: string, dst_perm := 0o755) -> (err: Error) {
+	temp_allocator := TEMP_ALLOCATOR_GUARD({})
+
+	csrc := clone_to_cstring(src, temp_allocator) or_return
+	cdst := clone_to_cstring(dst, temp_allocator) or_return
+
+	if darwin.copyfile(csrc, cdst, nil, darwin.COPYFILE_ALL + {.RECURSIVE}) < 0 {
+		err = _get_platform_error()
+	}
+
+	return
+}