* Add `no_trace` option to JSTraceable derive
* NoTrace wrapper
* Port some types to no_trace schematics
* Fixing my unsafe mistakes (not tracing traceables)
* Add docs & safety guards for no_trace
Safety guards (trait shenanigans) guarantees safety usage of `no_trace`
* Port canvas_traits to no_trace
* Port servo_media to no_trace
* Port net_traits to no_trace
* Port style to no_trace
* Port webgpu to no_trace
* Port script_traits to no_trace
* Port canvas_traits, devtools_traits, embedder_traits, profile_traits to no_trace
* unrooted_must_root lint in seperate file
* Add trace_in_no_trace_lint as script_plugin
* Composable types in must_not_have_traceable
* Introduced HashMapTracedValues wrapper
* `HashMap<NoTrace<K>,V>`->`HashMapTracedValues<K,V>`
* Port rest of servo's types to no_trace
* Port html5ever, euclid, mime and http to no_trace
* Port remaining externals to no_trace
* Port webxr and Arc<Mutex<_>>
* Fix spelling in notrace doc
This also removes the meta viewport support (which was implemented on top), but that also had a single test and is disabled everywhere, so I'm not too concerned, it can be implemented again if / when needed.
There are a few canvas2d-related dependencies that haven't updated, but they
only use euclid internally so that's not blocking landing the rest of the
changes.
Given the size of this patch, I think it's useful to get this landed as-is.
