Rewrite the script to create art tests in python.

This makes it easier to use on Windows and makes it a lot easier to
read and modify as well.

Change-Id: I9055014e722ae08ad9d907b450b6ca3f20401adf
diff --git a/build.gradle b/build.gradle
index 4caf5fa..37745576 100644
--- a/build.gradle
+++ b/build.gradle
@@ -295,13 +295,12 @@
 
 task createArtTests(type: Exec) {
     def outputDir = "build/generated/test/java/com/android/tools/r8/art"
-    def createArtTestsScript = "scripts/create-art-tests.sh"
+    def createArtTestsScript = "tools/create_art_tests.py"
     inputs.file "tests/art.tar.gz"
     inputs.file createArtTestsScript
     outputs.dir outputDir
     dependsOn downloadDeps
-    executable "bash"
-    args "${projectDir}/${createArtTestsScript}"
+    commandLine "${createArtTestsScript}"
     workingDir = projectDir
 }