[Adb] Don't always report stderr as a warning

Adb invocations are prone to returning non zero exit codes even when
they are successful. This can make our msbuild output a bit noisy[0] when
they are invoked using the Adb.cs task. The new optional parameter
`WriteOutputAsMessage` can now be provided to the adb task, so that we
don't always write messages coming from stderr as msbuild warnings. This
is used in our targets which wait for emulator startup to make it easier
to detect real failures in test instrumentation.

[0]
```
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_trace.cpp:192] Android Debug Bridge version 1.0.40 [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_trace.cpp:192] Version 28.0.2-5303910 [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_trace.cpp:192] Installed as /Users/peter/android-toolchain/sdk/platform-tools/adb [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_trace.cpp:192]  [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_client.cpp:287] adb_query: host-serial:emulator-5570:features [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_client.cpp:137] _adb_connect: host:version [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_io.cpp:107] writex: fd=3 len=16 30303063686f73743a76657273696f6e 000chost:version [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_io.cpp:81] readx: fd=3 wanted=4 [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_io.cpp:97] readx: fd=3 wanted=4 got=4 4f4b4159 OKAY [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_client.cpp:165] _adb_connect: return fd 3 [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_client.cpp:197] adb_connect: service host-serial:emulator-5570:features [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
  /Users/peter/source/pj/xamarin-android/build-tools/scripts/TestApks.targets(68,5): warning : adb D 04-29 15:10:48  3527 42649 adb_io.cpp:81] readx: fd=3 wanted=4 [/Users/peter/source/pj/xamarin-android/tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj]
```

Author: pjcollins

build-tools/Xamarin.Android.Tools.BootstrapTasks/Xamarin.Android.Tools.BootstrapTasks/Adb.cs

@@ -43,6 +43,7 @@ protected class CommandInfo
 		public                  bool            IgnoreExitCode        { get; set; }
 		public                  int             Timeout               { get; set; } = -1;
 		public                  string[]        EnvironmentVariables  { get; set; }
+		public                  bool            WriteOutputAsMessage  { get; set; } = false;
 
 		[Required]
 		public                  string          ToolPath              { get; set; }
@@ -147,7 +148,7 @@ void OnOutput (string line, bool isStdout, CommandInfo info)
 			lock (linesLock) lines.Add (line);
 
 			if (!info.SuppressMSbuildLog) {
-				if (isStdout)
+				if (isStdout || WriteOutputAsMessage)
 					Log.LogMessage (MessageImportance.Low, line);
 				else
 					Log.LogWarning (line);

build-tools/scripts/TestApks.targets

@@ -63,6 +63,7 @@
         ToolExe="$(AdbToolExe)"
         ToolPath="$(AdbToolPath)"
         Timeout="120000"
+        WriteOutputAsMessage="True"
     />
     <Xamarin.Android.Tools.BootstrapTasks.Adb
         EnvironmentVariables="ADB_TRACE=all"
@@ -72,6 +73,7 @@
         ToolExe="$(AdbToolExe)"
         ToolPath="$(AdbToolPath)"
         Timeout="120000"
+        WriteOutputAsMessage="True"
     />
     <Xamarin.Android.Tools.BootstrapTasks.Adb
         Arguments="$(_AdbTarget) shell setprop debug.mono.log timing"