Fixes servo#390
This feature is quite impactful as it is required for Tailwind's hover
styles to work.
Servo PR: servo/servo#45681
Signed-off-by: Nico Burns <nico@nicoburns.com>

Implements the `pointer`, `any-pointer`,`hover`, and `any-hover` media
features.
Actually detecting pointer capabilities from the system is left as a
follow-up (this is tricky as Winit doesn't expose this information).
This PR just configures Stylo with sensible defaults (mouse-like pointer
on desktop platforms, touch-like pointer on mobile platforms).
- ~Builds on: servo#44978 This has been
reordered - this PR is now first.
- Stylo PR: servo/stylo#391
Testing: WPT tests
Part of: servo#39068
Signed-off-by: Nico Burns <nico@nicoburns.com>

Fixes #390
This feature is quite impactful as it is required for Tailwind's hover
styles to work.
Servo PR: servo/servo#45681
Signed-off-by: Nico Burns <nico@nicoburns.com>