Includes C++26 related infrastructure macros.
Fixes compile errors when compiling under C++26.
Initially supported C++26 features:
- [[indeterminate]]
- new 2022 ISO prefixes in ratio.h
- atomic fetch_max() and fetch_min()
- is_virtual_base_of
- is_trivially_relocatable and trivially_relocate
- saturation arithmetic: add_sat, sub_sat, mul_sat, div_sat, saturate_cast
C++14 compiler compatibility
Updated test run scripts
Changed some ETL_ASSERT macros to ETL_ASSERT_OR_RETURN
Changed unit test macros for C++20 compaibility
Updated test run scripts
Updated CMake files to allow C++ standard selection
Replaced ETL_ASSERT_AND_RETURN with ETL_ASSERT_OR_RETURN
Updated C++14 & C++20 unit test compatibility
Changed native char8_t check
Added optional optimisation argument to bash script
