Add infra_tests.py, recipe, buildbotless bot

infra/bots/recipes/swarm_infra.expected/infra_tests.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys, os\npath = sys.argv[1]\nmode = int(sys.argv[2])\nif not os.path.isdir(path):\n  if os.path.exists(path):\n    print \"%s exists but is not a dir\" % path\n    sys.exit(1)\n  os.makedirs(path, mode)\n",
       "[CUSTOM_/_B_WORK]",
       "511"
     ],
     "name": "makedirs checkout_path",
@@ skipping 103 matching lines @@
     "env": {
       "BUILDTYPE": "Release",
       "CHROME_HEADLESS": "1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]:RECIPE_PACKAGE_REPO[depot_tools]",
       "SKIA_OUT": "[SLAVE_BUILD]/out"
     },
     "name": "gclient recurse (git config user.email)"
   },
   {
     "cmd": [
-      "git",
-      "status"
+      "go",
+      "get",
+      "-u",
+      "go.skia.org/infra/..."
     ],
-    "cwd": "[CUSTOM_/_B_WORK]/skia",
-    "name": "git status"
+    "env": {
+      "GOPATH": "[CUSTOM_/_B_WORK]/gopath"
+    },
+    "name": "update_go_pkgs"
   },
   {
     "cmd": [
-      "RECIPE_PACKAGE_REPO[depot_tools]/presubmit_support.py",
-      "--commit",
-      "--upstream=HEAD^",
-      "-v",
-      "-v"
+      "python",
+      "[CUSTOM_/_B_WORK]/skia/infra/bots/infra_tests.py"
     ],
     "cwd": "[CUSTOM_/_B_WORK]/skia",
     "env": {
-      "PATH": "RECIPE_PACKAGE_REPO[depot_tools]:%(PATH)s"
+      "GOPATH": "[CUSTOM_/_B_WORK]/gopath"
     },
-    "name": "presubmit"
+    "name": "infra_tests"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]