[libc++][ranges] Implement `lazy_split_view`.

Note that this class was called just `split_view` in the original One
Ranges Proposal and was renamed to `lazy_split_view` by
[P2210](https://wg21.link/p2210).

Co-authored-by: zoecarver <z.zoelec2@gmail.com>

Differential Revision: https://reviews.llvm.org/D107500

NOKEYCHECK=True
GitOrigin-RevId: e53c461bf3f0feebb4fd6b43e05a0047f8edb945
diff --git a/include/module.modulemap b/include/module.modulemap
index 80ebbaf..6a20165 100644
--- a/include/module.modulemap
+++ b/include/module.modulemap
@@ -851,6 +851,7 @@
       module enable_view            { private header "__ranges/enable_view.h" }
       module iota_view              { private header "__ranges/iota_view.h" }
       module join_view              { private header "__ranges/join_view.h" }
+      module lazy_split_view        { private header "__ranges/lazy_split_view.h" }
       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" }