* update: Migrate off legacy JS/HTML apis
* update: use dart.library.js_interop in place of dart.library.html
* update: dart format xhr_transport.dart and update dart sdk to v3.4.0 in workflows
* update: use if instead of switch case in xhr_transport.dart
* update: upgrade web package to v1.1.0
* refactor: use Uint8List for sending data over XHR rather than Int8List
* refactor: eta-reduction of call to request.setRequestHeader
* Update client_xhr_transport_test to avoid dart:html, updating xhr_transport to support testability
* fixup tests
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Co-authored-by: minoic <minoic2020@gmail.com>
Co-authored-by: Moritz <mosum@google.com>