Clipboard refactoring
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This PR removes clipboard handling from the constellation. Instead, now embedder handles it.
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- [X] `./mach build -d` does not report any errors
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- [X] These changes fix#23440 (GitHub issue number if applicable)
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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because it is enough to test manually in input box, if copying and pasting still works .
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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
