- Update g++ module testing to use g++ version 15 instead of 14.
The module support in version 14 isn't very stable and the module
testing was not working due to unresolved locale symbols.
- Update CI for linux and macos to add verbosity so its consistent with
windows.
- Refactor test/CMakeLists.txt to enable testing for modules
- The tests in `module-test.cc` seem to not have been updated in some
time despite changes in the main library.
- Wide String versions of several tests appear to be deprecated so have
been removed.
- Refactored tests related to `fmt::format_args` that now requires lvalue
references as opposed to direct values.
- Remove the none-working code identified in the `module-test.cc` file
while updating.
* use the standard `test-main.cc` component instead of injected test infrastructure sources
* undo now obsolete commit `00235d8a` from July 2021
* Clang cannot import user-defined literals as it seems -> disable test
* Clang emits duplicate, non-mergeable copies of `detail::buffer`'s vtable, causing linker errors -> disable test
