Make git recipe api add depot_tools to PATH

recipe_modules/git/example.expected/platform_win.json

 [
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[depot_tools]\\bootstrap\\win\\win_tools.bat"
     ],
     "cwd": "RECIPE_PACKAGE_REPO[depot_tools]",
     "name": "ensure git tooling on windows",
     "timeout": 300
   },
   {
@@ skipping 13 matching lines @@
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[depot_tools]\\git.bat",
       "retry",
       "fetch",
       "origin",
       "master",
       "--recurse-submodules"
     ],
     "cwd": "[SLAVE_BUILD]\\src",
+    "env": {
+      "PATH": "RECIPE_PACKAGE_REPO[depot_tools];%(PATH)s"
+    },
     "name": "git fetch"
   },
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[depot_tools]\\git.bat",
       "checkout",
       "-f",
       "FETCH_HEAD"
     ],
     "cwd": "[SLAVE_BUILD]\\src",
@@ skipping 134 matching lines @@
     ],
     "cwd": "[SLAVE_BUILD]\\src",
     "name": "git bundle"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]