<!-- Please describe your changes on the following line: -->
This patch depends on the [devices mock device support PR](https://github.com/servo/devices/pull/17).
After it lands, the Cargo files can be updated.
1. Adjust to the changes in [devices mock device support PR](https://github.com/servo/devices/pull/17).
2. WebBluetooth Test API implementation. Based on : https://webbluetoothcg.github.io/web-bluetooth/tests.html
3. Wpt tests for the already landed WebBluetooth functions.
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
<!-- Either: -->
- [x] There are tests for these changes
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Source-Repo: https://github.com/servo/servo
Source-Revision: dae007fd1634bcf1545e67abaa7746fa95f10e94
