Fixes https://github.com/flutter/flutter/issues/139709
This adds a static helper method `ProcessUtils.writelnToStdinGuarded()`, which will asynchronously write to a sub-process's STDIN `IOSink` and catch errors.
In talking with Brian, it sounds like this is the best and most reliable way to catch `SocketException`s during these writes *to sub-process file descriptors* specifically (with a "real" hard drive file, the future returned by `.flush()` should complete with the write error).
Also, as I note in the dartdoc to `writelnToStdinGuarded()`, the behavior seems to be different between macOS and linux.
Moving forward, in any place where we want to catch exceptions writing to STDIN, we will want to use this new helper.
Adding debugging for https://github.com/flutter/flutter/issues/129836.
Takes a screenshot when startup test takes too long (10 minutes).
Also, removes some old debugging and add new debugging message.
This reverts commit a19b3436ee.
We added this logging to try and determine if the reason for Dart VM errors (https://github.com/flutter/flutter/issues/121231) was caused by some issue with the streams.
A recent test proves that is not the case:
https://ci.chromium.org/ui/p/flutter/builders/prod/Mac_ios%20platform_view_ios__start_up/11046/overview
The test shows the Dart VM url in the device log. However, the test log does NOT show a log for the Dart VM url but does show the stack trace, which all come from the main stream, which means it's not an issue with the secondary streams not receiving the log.
So reverting the debugging we added.
Log all output of `ios-deploy` to try and determine if the issue of https://github.com/flutter/flutter/issues/121231 is with stream or with `ios-deploy`.
Note: This will cause some duplicate logs like example below but only in verbose mode
```
(lldb) 2023-05-19 13:48:19.107935-0500 Runner[2521:390363] [VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(35)] Using the Impeller rendering backend.
(lldb) 2023-05-19 13:48:19.107935-0500 Runner[2521:390363] [VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(35)] Using the Impeller rendering backend.
2023-05-19 13:48:19.156866-0500 Runner[2521:390612] flutter: The Dart VM service is listening on http://127.0.0.1:63508/IsFnhXJykCM=/
VM Service URL on device: http://127.0.0.1:63508/IsFnhXJykCM=/
```
Check what is available in the device's iOS DeviceSupport folder to check if symbols were properly fetched. Also, add some logging to track what status the debugger is in.
Debugging for https://github.com/flutter/flutter/issues/121231.
Our current top crasher is an unclear error when ProcessManager fails to resolve an executable path. To fix this, we'd like to being adjusting the process resolution logic and adding more instrumentation to track failures. In order to begin the process, the ProcessManager has been folded back into the flutter tool
