Cronvoy: getStatus

The Cronet API exposes a peculiar [```UrlRequest.getStatus method```](https://chromium.googlesource.com/chromium/src/+/main/components/cronet/android/api/src/org/chromium/net/UrlRequest.java#410). The Engine "C++ layer" is asked to return its status, however the value is returned by invoking the provided callback method, which will use the Executor passed when creating the UrlRequest. The C++ layer schedules the callback with the [```CronetURLRequestAdapter::GetStatus method```](https://chromium.googlesource.com/chromium/src/+/refs/heads/main/components/cronet/android/cronet_url_request_adapter.cc#155). This is the callback class:
```
public abstract static class StatusListener {
// Invoked on {@link UrlRequest}'s {@link Executor}'s thread when request
// status is obtained.
// @param status It is one of the values defined in {@link Status}.
public abstract void onStatus(int status);
}
```

And those are the possible [status values](https://source.chromium.org/chromium/chromium/src/+/main:components/cronet/android/api/src/org/chromium/net/UrlRequest.java;l=232):

- ```INVALID = -1```
- ```IDLE = 0```
- ```WAITING_FOR_STALLED_SOCKET_POOL = 1``` // No reference in google code base
- ```WAITING_FOR_AVAILABLE_SOCKET = 2``` // No reference in google code base
- ```WAITING_FOR_DELEGATE = 3``` // No reference in google code base
- ```WAITING_FOR_CACHE = 4``` // No reference in google code base
- ```DOWNLOADING_PAC_FILE = 5``` // No reference in google code base
- ```RESOLVING_PROXY_FOR_URL = 6``` // No reference in google code base
- ```RESOLVING_HOST_IN_PAC_FILE = 7``` // No reference in google code base
- ```ESTABLISHING_PROXY_TUNNEL = 8``` // No reference in google code base
- ```RESOLVING_HOST = 9``` // No reference in google code base
- ```CONNECTING = 10```
- ```SSL_HANDSHAKE = 11```
- ```SENDING_REQUEST = 12```
- ```WAITING_FOR_RESPONSE = 13```
- ```READING_RESPONSE = 14``` // No reference in google code base

Requires changes in Envoy.

This is used by AGSA (Android Google Search App), and an Android library maintained by Google also uses this: [ExoPlayer](https://github.com/google/ExoPlayer/blob/release-v2/extensions/cronet/src/main/java/com/google/android/exoplayer2/ext/cronet/CronetDataSource.java#L988). This does not seem to drive business logic - only informational.

It is suspected that implementing only some of the status would be fine.