node: Use a RefCell for the State

We can remove the use of a raw pointer and use RefCell instead.
Since the state is now only mutable internally, we need to move
the parse_style_attributes method on the node itself.
This also allows to remove the manual Drop implementation of Node.
3 jobs from state in 9 minutes and 26 seconds (queued for 26 minutes and 57 seconds)
Status Job ID Name Coverage
  Test
passed #95734
fedora test

00:09:03

 
  Lint
manual #95736
allowed to fail manual
clippy
passed #95735
rustfmt

00:00:22