Auto merge of #13612 - szeged:test-api-impl, r=jdm

WebBluetooth Test API and tests

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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.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors

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- [x] There are tests for these changes

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