Auto merge of #11523 - szeged:random_id, r=jdm

Add random Device ID generation

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The [spec](https://webbluetoothcg.github.io/web-bluetooth/#add-an-allowed-bluetooth-device) (2. step) defines that the device id can't be the public address, therefore we generate a random id.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because there are no webbluetooth test api implementation yet.

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components/net/Cargo.toml

@@ -30,6 +30,7 @@ openssl = "0.7.6"
 openssl-verify = "0.1"
 plugins = {path = "../plugins"}
 profile_traits = {path = "../profile_traits"}
+rand = "0.3"
 rustc-serialize = "0.3"
 threadpool = "1.0"
 time = "0.1.17"