The existing ad-hoc logic was not quite correct because it didn’t eg. remove `-MT/depfile` because it assumed that `-MT` was followed by a space. It also didn’t take into account that `serialize-diagnostics` can be spelled with a single dash or two dashes.
Create a `CompilerCommandLineOption` type that forces decisions to be made about the dash spelling and argument styles, which should help avoid problems like this in the future.
