[Skia] Convert SKPs to a CIPD package

scripts/slave/recipes/skia/swarm_test.expected/download_and_push_skimage.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/skia/tools/buildbot_spec.py",
       "/path/to/tmp/json",
       "Test-Android-GCC-Nexus7-GPU-Tegra3-Arm7-Debug"
     ],
     "cwd": "[SLAVE_BUILD]/skia",
@@ skipping 254 matching lines @@
       "SKIA_ANDROID_VERBOSE_SETUP": "1",
       "SKIA_OUT": "[SLAVE_BUILD]/out"
     },
     "name": "push resources"
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
-      "[SLAVE_BUILD]/tmp/SKP_VERSION",
+      "[SLAVE_BUILD]/skia/infra/bots/assets/skp/VERSION",
       "/path/to/tmp/"
     ],
-    "name": "Get downloaded SKP_VERSION"
+    "name": "Get downloaded SKP VERSION"
   },
   {
     "cmd": [
+      "python",
+      "-u",
+      "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
+      "42",
+      "[SLAVE_BUILD]/tmp/SKP_VERSION"
+    ],
+    "name": "write SKP_VERSION"
+  },
+  {
+    "cmd": [
       "[SLAVE_BUILD]/android_sdk/android-sdk/platform-tools/adb",
       "shell",
       "cat",
       "/storage/emulated/legacy/skiabot/skia_tmp_dir/SKP_VERSION"
     ],
     "env": {
       "BUILDTYPE": "Debug",
       "CHROME_HEADLESS": "1",
       "GYP_DEFINES": "skia_arch_type=arm skia_warnings_as_errors=0",
       "PYTHONPATH": "[BUILD]/scripts",
@@ skipping 510 matching lines @@
       "SKIA_OUT": "[SLAVE_BUILD]/out"
     },
     "name": "kill-server"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]