Remove cxx feature checks that are already in c++17 standard library

Summary

This MR removes some c++ feature checks from cmake, since the features are already standard:

• DUNE_HAVE_CXX_BOOL_CONSTANT
• DUNE_HAVE_CXX_EXPERIMENTAL_BOOL_CONSTANT
• DUNE_HAVE_HEADER_EXPERIMENTAL_TYPE_TRAITS
• DUNE_HAVE_CXX_APPLY
• DUNE_HAVE_CXX_EXPERIMENTAL_APPLY
• HAVE_IS_INDEXABLE_SUPPORT

The fallback implementations are removed and the inclusion into the Dune::Std namespace is marked deprecated. This does typically not work for using declarations. Thus, the functions are marked deprecated in Doxygen only.

added 1 commit

• 8ad7f30c - remove cxx feature checks that are already in c++17 standard library

Compare with previous version

changed the description

changed milestone to %New CMake Build-System

removed milestone %New CMake Build-System

changed the description

resolved all threads

added 1 commit

• c6d551b9 - Apply 2 suggestion(s) to 2 file(s)

Compare with previous version

added cleanup label

Great, this MR handles some quite old code. Do mind adding the removed C++ types to the change log? And maybe squashing the commits would make it cleaner.

added 1 commit

• a26d05bd - remove cxx feature checks that are already in c++17 standard library

Compare with previous version

Checked all core modules, see https://gitlab.dune-project.org/infrastructure/dune-nightly-test/-/pipelines/34572

resolved all threads

merged

mentioned in commit f1bec4e4

mentioned in issue #199 (closed)

mentioned in issue #234 (closed)

mentioned in issue #251 (closed)