gh-115942: Add locked to several multiprocessing locks (#115944)

Co-authored-by: mpage <mpage@cs.stanford.edu>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Lib/importlib/_bootstrap.py

@@ -382,6 +382,9 @@ class _ModuleLock:
                     self.waiters.pop()
                     self.wakeup.release()
 
+    def locked(self):
+        return bool(self.count)
+
     def __repr__(self):
         return f'_ModuleLock({self.name!r}) at {id(self)}'