Fix test array sizes
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
