Add simple build archiving for Mandoline binaries.

scripts/slave/recipes/chromium_mojo.expected/full_chromium_mojo_Chromium_Mojo_Linux.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "chromium.mojo",
       "--builder",
       "Chromium Mojo Linux",
@@ skipping 458 matching lines @@
       "python",
       "-u",
       "[SLAVE_BUILD]/src/mojo/tools/apptest_runner.py",
       "[SLAVE_BUILD]/src/out/Release",
       "--verbose"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "app_tests"
   },
   {
+    "cmd": [
+      "cat",
+      "[SLAVE_BUILD]/src/chrome/VERSION"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "get version",
+    "stdout": "/path/to/tmp/version",
+    "~followup_annotations": [
+      "@@@STEP_TEXT@Found version 37.0.2021.0@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[gsutil]/resources/gsutil_wrapper.py",
+      "--",
+      "[DEPOT_TOOLS]/gsutil.py",
+      "----",
+      "ls",
+      "gs://mandoline/"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "gsutil ls gs://mandoline/",
+    "stdout": "/path/to/tmp/",
+    "~followup_annotations": [
+      "@@@STEP_LOG_LINE@ls result stdout@@@@",
+      "@@@STEP_LOG_END@ls result stdout@@@"
+    ]
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
+      "[SLAVE_BUILD]/src/mandoline/tools/data/FILES.cfg",
+      "/path/to/tmp/"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "read FILES.cfg"
+  },
+  {
+    "cmd": [
+      "python",
+      "-u",
+      "RECIPE_MODULE[gsutil]/resources/gsutil_wrapper.py",
+      "--",
+      "[DEPOT_TOOLS]/gsutil.py",
+      "----",
+      "cp",
+      "[SLAVE_BUILD]/src/out/Release/foo",
+      "gs://mandoline/37.0.2021.0/linux/foo"
+    ],
+    "cwd": "[SLAVE_BUILD]",
+    "name": "gsutil upload",
+    "~followup_annotations": [
+      "@@@STEP_LINK@gsutil.upload@https://storage.cloud.google.com/mandoline/37.0.2021.0/linux/foo@@@"
+    ]
+  },
+  {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]