[libcxx][ranges] Add `std::ranges::single_view`.

Differential Revision: https://reviews.llvm.org/D106840

NOKEYCHECK=True
GitOrigin-RevId: 481ad59b9fa467882873dd7e45645e613cb77786
diff --git a/include/module.modulemap b/include/module.modulemap
index cd77a4a..ee6f3c3 100644
--- a/include/module.modulemap
+++ b/include/module.modulemap
@@ -632,6 +632,7 @@
       module non_propagating_cache  { private header "__ranges/non_propagating_cache.h" }
       module ref_view               { private header "__ranges/ref_view.h"              }
       module size                   { private header "__ranges/size.h"                  }
+      module single_view            { private header "__ranges/single_view.h"           }
       module subrange               { private header "__ranges/subrange.h"              }
       module take_view              { private header "__ranges/take_view.h"             }
       module transform_view         { private header "__ranges/transform_view.h"        }