rules: Fix wild card handling

[wismill]

The handling of wild card * is different in libxkbfile and X server: wild card matches empty strings for model and option but not for layout nor variant, while in libxkbcommon wild cards always match empty strings.

See:

• https://gitlab.freedesktop.org/xorg/lib/libxkbfile/-/blob/bf985c68acb1244f51ec91414532a2347fbc1c4c/src/maprules.c#L687
• https://gitlab.freedesktop.org/xorg/lib/libxkbfile/-/blob/bf985c68acb1244f51ec91414532a2347fbc1c4c/src/maprules.c#L712

The difference of handling between the components is unfortunately not documented, but we should follow the behavior of the original implementations for consistency.

• Fixed by implementing the same behavior than libxkbfile.
• Added tests and fixed failing tests.

Fixes #497

[whot]

let's cc @daniels and @bluetech explicitly, if this differs from the original implementation there may be a reason for it they remember?

[wismill]

@fooishbar @bluetech kind reminder 🙂