[libc++][ranges] Implement rbegin, rend, crbegin and crend.

Differential Revision: https://reviews.llvm.org/D119057

NOKEYCHECK=True
GitOrigin-RevId: 55bd22f853d8acbfabdfd1086fa4f4d97db71f63
diff --git a/include/module.modulemap b/include/module.modulemap
index 5727053..0ef457a 100644
--- a/include/module.modulemap
+++ b/include/module.modulemap
@@ -815,7 +815,9 @@
       module non_propagating_cache  { private header "__ranges/non_propagating_cache.h" }
       module owning_view            { private header "__ranges/owning_view.h" }
       module range_adaptor          { private header "__ranges/range_adaptor.h" }
+      module rbegin                 { private header "__ranges/rbegin.h" }
       module ref_view               { private header "__ranges/ref_view.h" }
+      module rend                   { private header "__ranges/rend.h" }
       module reverse_view           { private header "__ranges/reverse_view.h" }
       module single_view            { private header "__ranges/single_view.h" }
       module size                   { private header "__ranges/size.h" }