script_bindings: Assert that serializable/transferable types have accurate WebIDL annotations (#38615)

These changes add compile-time assertions that:
* any type that implements the Serializable/Transferable trait has a
`[Serializable]` or `[Transferable]` annotation in the interface WebIDL
* any WebIDL interface with the `[Serializable]` or `[Transferable]`
annotation implements the corresponding trait

This is useful because it means that WebIDL definitions will be less
confusing if you're trying to figure out whether Servo supports
serializing/transferring a particular interface type. It also makes
fixing #21715 in the future a little bit easier, because the annotations
will remain up to date.

Testing: compile-time only; no point in writing tests for this since it
involves webidl codegen.

---------

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

components/script_bindings/webidls/DOMRectReadOnly.webidl

@@ -5,7 +5,7 @@
 // https://drafts.fxtf.org/geometry/#domrect
 
 [Exposed=(Window,Worker),
- Serializable]
+ /*Serializable*/]
 interface DOMRectReadOnly {
   [Throws] constructor(optional unrestricted double x = 0, optional unrestricted double y = 0,
               optional unrestricted double width = 0, optional unrestricted double height = 0);