Build secure Rust watchOS TOTP core (#56)

apple/Generated/ironstorage_watch.modulemap

@@ -0,0 +1,7 @@
+module ironstorage_watch {
+    header "ironstorage_watchFFI.h"
+    export *
+    use "Darwin"
+    use "_Builtin_stdbool"
+    use "_Builtin_stdint"
+}