[libc++] Implement P1425R4 (Iterator pair constructors for std::stack and std::queue)

Implement P1425R4

Reviewed By: Quuxplusone, #libc, Mordante

Spies: Mordante, jloser, libcxx-commits, arichardson

Differential Revision: https://reviews.llvm.org/D115977

NOKEYCHECK=True
GitOrigin-RevId: f3aed3698185dd4a03b210a9d73be4dc1efc580f
diff --git a/docs/FeatureTestMacroTable.rst b/docs/FeatureTestMacroTable.rst
index 714ed80..40e7558 100644
--- a/docs/FeatureTestMacroTable.rst
+++ b/docs/FeatureTestMacroTable.rst
@@ -296,6 +296,8 @@
     ------------------------------------------------- -----------------
     **C++ 2b**
     -------------------------------------------------------------------
+    ``__cpp_lib_adaptor_iterator_pair_constructor``   ``202106L``
+    ------------------------------------------------- -----------------
     ``__cpp_lib_allocate_at_least``                   *unimplemented*
     ------------------------------------------------- -----------------
     ``__cpp_lib_associative_heterogeneous_erasure``   *unimplemented*
diff --git a/docs/Status/Cxx2bPapers.csv b/docs/Status/Cxx2bPapers.csv
index 7a76e1f..50b11c4 100644
--- a/docs/Status/Cxx2bPapers.csv
+++ b/docs/Status/Cxx2bPapers.csv
@@ -15,7 +15,7 @@
 "`P0448R4 <https://wg21.link/P0448R4>`__","LWG","A strstream replacement using span<charT> as buffer","June 2021","",""
 "`P1132R8 <https://wg21.link/P1132R8>`__","LWG","out_ptr - a scalable output pointer abstraction","June 2021","",""
 "`P1328R1 <https://wg21.link/P1328R1>`__","LWG","Making std::type_info::operator== constexpr","June 2021","",""
-"`P1425R4 <https://wg21.link/P1425R4>`__","LWG","Iterators pair constructors for stack and queue","June 2021","",""
+"`P1425R4 <https://wg21.link/P1425R4>`__","LWG","Iterators pair constructors for stack and queue","June 2021","|Complete|","14.0"
 "`P1518R2 <https://wg21.link/P1518R2>`__","LWG","Stop overconstraining allocators in container deduction guides","June 2021","|Complete|","13.0"
 "`P1659R3 <https://wg21.link/P1659R3>`__","LWG","starts_with and ends_with","June 2021","",""
 "`P1951R1 <https://wg21.link/P1951R1>`__","LWG","Default Arguments for pair Forwarding Constructor","June 2021","|Complete|","14.0"