[libc++][ranges] Implement `std::sortable`.

Differential Revision: https://reviews.llvm.org/D119619

NOKEYCHECK=True
GitOrigin-RevId: 8e979460bb27610d574733ca5b75afae0cdfb3c9
diff --git a/include/module.modulemap b/include/module.modulemap
index ea05075..890b7fe 100644
--- a/include/module.modulemap
+++ b/include/module.modulemap
@@ -640,6 +640,7 @@
       module reverse_access        { private header "__iterator/reverse_access.h" }
       module reverse_iterator      { private header "__iterator/reverse_iterator.h" }
       module size                  { private header "__iterator/size.h" }
+      module sortable              { private header "__iterator/sortable.h" }
       module unreachable_sentinel  { private header "__iterator/unreachable_sentinel.h" }
       module wrap_iter             { private header "__iterator/wrap_iter.h" }
     }