[Feature] --clear and --clean flags

I have been doing an experiment with implementing a --clean and --clear command. I ran into this issue on Windows where I was trying various compilers and had to often clear the cache to test if everything worked out of the box when doing cmake ...

• The --clean command deletes CMakeCache.txt and CMakeFiles/** (this is to prevent deletion of _deps and other downloaded things that I would like to keep)
• The --clear command does rm -rf * (there is no nice command for this in Windows and it's easier to have it in CMake because I only ever use it to clear a build directory)

I know you can probably do this with cmake -E, but it would be cool if you could have an alias.clean command like git.

If anyone would like to try here is part of the code that implements it:

HOOK_ENTRYPOINT()
{
	dlog();
	auto commandLine = GetCommandLineW();
	if (wcsstr(commandLine, L" --clean"))
	{
		auto FileExists = [](const wchar_t* szFileName)
		{
			return GetFileAttributesW(szFileName) != INVALID_FILE_ATTRIBUTES;
		};
		bool cacheDeleted = true;
		if (FileExists(L"CMakeCache.txt"))
		{
			if (system("del CMakeCache.txt > nul 2>&1") != 0)
			{
				cacheDeleted = false;
				puts("Failed to delete CMakeCache.txt");
			}
		}
		bool filesDeleted = true;
		if (FileExists(L"CMakeFiles"))
		{
			if (system("rmdir /q /s CMakeFiles") != 0)
			{
				filesDeleted = false;
			}
		}
		return filesDeleted && cacheDeleted ? EXIT_SUCCESS : EXIT_FAILURE;
	}
	else if (wcsstr(commandLine, L"--clear"))
	{
		// TODO: nicer error handling
		// Thanks to Jonas for the help with the command
		system("rmdir /s /q . > nul 2>&1 & dir /b");
		return 0;
	}
	return original_EntryPoint();
}

(It will also properly signal to the user if there was any kind of issue deleting files, which happens when you leave Visual Studio open for instance).