Migrate from `dart:html` to `package:web` #2143

Job	Run time
dartanalyze	59s
build (macos)	7m 43s
build (linux)	5m 17s
build (windows)	7m 29s
clippy (linux)	2m 59s
dartfmt	52s
clippy (macos)	3m 19s
clippy (windows)	5m 25s
ktfmt	11s
rustdoc (linux)	2m 55s
rustdoc (macos)	3m 4s
rustfmt	13s
swiftformat	10s
rustdoc (windows)	5m 22s
test (example, ${{ matrix.platform }})	1s
dart pub publish (pub.dev)	1s
pr	1s
release (GitHub)	1s
	46m 2s

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