MountRule: Relaxing constraints on fstype and completing AARE support
- Before this commit, fstype had to match a known fs. However, having and maintaining the exhaustive list of fstypes proved challenging (see !1195 (merged) and !1176 (merged)). Therefore, we add support for any filesystem name.
- Completing AARE support for fstype (brace expressions like ext{3,4} are now supported).