Auto merge of #21881 - pyfisch:keyboard-types, r=paulrouget

Use keyboard-types crate

Have embedders send DOM keys to servo and use a strongly typed KeyboardEvent
from the W3C UI Events spec. All keyboard handling now uses the new types.

Introduce a ShortcutMatcher to recognize key bindings. Shortcuts are now
recognized in a uniform way.

Updated the winit port.
Updated webdriver integration.

part of #20331

What this PR does:

* allow the use non-ASCII keyboards for text input
* decouple keyboard event "key" from "code" (key meaning vs location)

What this PR does not do:

* completely improve keyboard events send from winit and webdriver
* add support for CompositionEvent or IME

Notes:

* The winit embedder does not send keyup events for printable keys (this is a regression)
* keyboard-types is on crates.io because I believe it to be useful outside of servo. If you prefer I can add a copy in this repo.

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components/script/lib.rs

@@ -54,6 +54,7 @@ extern crate image;
 extern crate ipc_channel;
 #[macro_use]
 extern crate jstraceable_derive;
+extern crate keyboard_types;
 #[macro_use]
 extern crate lazy_static;
 extern crate libc;