Mostly remove pre-CXX11 workarounds.

С++03 support was deprecated in 1.85 and now can be removed. This PR clears
many of workarounds, which are no longer needed now.

* Remove unused workaround macros (many of).
* Remove BOOST_STATIC_ASSERT usages.
* Minimize Boost::type_traits dependency (in favour of STL's type_traits).

Closes https://github.com/boostorg/iterator/pull/82.

Squashed commit of the following:

commit 741a627b73
Author: Georgy Guminov <gogagum@gmail.com>
Date:   Sat Jan 25 12:13:05 2025 +0300

    Replace testers with standard metafunctions.

commit bf4cce6114
Author: Georgy Guminov <gogagum@gmail.com>
Date:   Sat Jan 25 11:51:32 2025 +0300

    Refactor is_lvalue_iterator.hpp.

commit 8d080c6c58
Author: Georgy Guminov <gogagum@gmail.com>
Date:   Sat Jan 25 10:27:32 2025 +0300

    Remove more workarounds.

commit 5a4ba24d36
Author: Georgy Guminov <gogagum@gmail.com>
Date:   Sun Jan 19 16:38:30 2025 +0300

    Fixes.

commit fdfafce2b9
Author: Georgy Guminov <gogagum@gmail.com>
Date:   Sat Oct 26 15:06:43 2024 +0300

    Remove BOOST_NO_STRICT_ITERATOR_INTEROPERABILITY
    Correct static_assert messages.
    Fix messages & replace is_standard_layout with is_copy_constructible.

commit c69ac1408a
Author: Georgy Guminov <gogagum@gmail.com>
Date:   Sat Oct 26 14:48:51 2024 +0300

    Correct static_assert messages.

commit b5df827151
Author: Georqy Guminov <gogagum@gmail.com>
Date:   Sun Jun 23 16:12:29 2024 +0300

    Fixes. Remove some Boost.MPL usages. Remove unused includes.

commit 01fd35e9f8
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Wed Jun 12 17:14:21 2024 +0300

    abstract conjunction.

commit c02def8acf
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Wed Jun 12 16:35:43 2024 +0300

    return addressof & conjunction.

commit 3b3d162575
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Wed Jun 12 16:30:44 2024 +0300

    Make macro more readable.

commit 4ab19e045f
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Wed Jun 12 15:56:49 2024 +0300

    Add static_assert messages.

commit 82b5c44cd3
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Wed Jun 12 14:12:10 2024 +0300

    Return is iterator CXX17 test.

commit 2d58d65462
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Tue Jun 11 14:04:17 2024 +0300

    Omitted.

commit a0d04d9491
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Tue Jun 11 14:00:35 2024 +0300

    Replace move with static_cast

commit 4a49b8a1a2
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Mon Jun 10 21:38:53 2024 +0300

    Return BOOST_NOEXCEPT

commit 054c013bba
Author: Georgiy Guminov <gogagum@gmail.com>
Date:   Sun Jun 9 15:20:41 2024 +0300

    CXX11

include/boost/iterator/interoperable.hpp

@@ -7,12 +7,7 @@
 #ifndef BOOST_INTEROPERABLE_23022003THW_HPP
 # define BOOST_INTEROPERABLE_23022003THW_HPP
 
-# include <boost/mpl/bool.hpp>
-# include <boost/mpl/or.hpp>
-
-# include <boost/type_traits/is_convertible.hpp>
-
-# include <boost/iterator/detail/config_def.hpp> // must appear last
+# include <boost/iterator/detail/type_traits/disjunction.hpp>
 
 namespace boost {
 namespace iterators {
@@ -33,13 +28,7 @@ namespace iterators {
   //
   template <typename A, typename B>
   struct is_interoperable
-# ifdef BOOST_NO_STRICT_ITERATOR_INTEROPERABILITY
-    : mpl::true_
-# else
-    : mpl::or_<
-          is_convertible< A, B >
-        , is_convertible< B, A > >
-# endif
+    : detail::disjunction<std::is_convertible<A, B>, std::is_convertible<B, A>>
   {
   };
 
@@ -49,6 +38,4 @@ using iterators::is_interoperable;
 
 } // namespace boost
 
-# include <boost/iterator/detail/config_undef.hpp>
-
 #endif // BOOST_INTEROPERABLE_23022003THW_HPP