[Mammoth] Move Mutex and Semaphore to a separate folder.

lib/mammoth/sync/mutex.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <glacier/status/error_or.h>
+#include <ztypes.h>
+
+class Mutex {
+ public:
+  Mutex(const Mutex&) = delete;
+  Mutex(Mutex&&);
+  Mutex& operator=(Mutex&&);
+
+  static glcr::ErrorOr<Mutex> Create();
+
+  glcr::ErrorCode Lock();
+  glcr::ErrorCode Release();
+
+ private:
+  z_cap_t mutex_cap_;
+
+  Mutex(z_cap_t mutex_cap) : mutex_cap_(mutex_cap) {}
+};