Populate exit code for Windows targets

This is a follow up of https://flutter-review.googlesource.com/c/recipes/+/54925 to pupulate exit code for Windows targets.

LED run: https://ci.chromium.org/raw/build/logs.chromium.org/flutter/led/keyonghan_google.com/fd66238b64178e8132898bdad25ee775d9827e0a5420d530d1bac5ae37750067/+/build.proto?server=chromium-swarm.appspot.com

Change-Id: Ief155b9f4bbe9bb56b041e7c9d62d65f3bbaf9d4
Bug: https://github.com/flutter/flutter/issues/142998
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/54932
Reviewed-by: Godofredo Contreras <godofredoc@google.com>
Commit-Queue: Godofredo Contreras <godofredoc@google.com>

recipe_modules/test_utils/resources/runner.ps1

diff --git a/recipe_modules/test_utils/resources/runner.ps1 b/recipe_modules/test_utils/resources/runner.ps1
index 41cc2b7..3e54946 100644
--- a/recipe_modules/test_utils/resources/runner.ps1
+++ b/recipe_modules/test_utils/resources/runner.ps1
@@ -10,3 +10,4 @@
 }
 Write-Host $cmd
 iex $cmd | Set-Content $Env:LOGS_FILE -Passthru
+exit $LASTEXITCODE
\ No newline at end of file