Reland of depot_tools: add infra_paths recipe module for infra-specific paths

recipe_modules/tryserver/example.expected/with_git_patch.json

 [
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]/scripts/slave/git_setup.py",
+      "[ROOT]/b/build/scripts/slave/git_setup.py",
       "--path",
-      "[TMP_BASE]/patch_tmp_1",
+      "[TMP]/patch_tmp_1",
       "--url",
       "http://patch.url/"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "patch git setup"
   },
   {
     "cmd": [
       "git",
       "fetch",
       "origin",
       "johndoe#123.diff"
     ],
-    "cwd": "[TMP_BASE]/patch_tmp_1",
+    "cwd": "[TMP]/patch_tmp_1",
     "name": "patch fetch"
   },
   {
     "cmd": [
       "git",
       "clean",
       "-f",
       "-d",
       "-x"
     ],
-    "cwd": "[TMP_BASE]/patch_tmp_1",
+    "cwd": "[TMP]/patch_tmp_1",
     "name": "patch clean"
   },
   {
     "cmd": [
       "git",
       "checkout",
       "-f",
       "FETCH_HEAD"
     ],
-    "cwd": "[TMP_BASE]/patch_tmp_1",
+    "cwd": "[TMP]/patch_tmp_1",
     "name": "patch git checkout"
   },
   {
     "cmd": [
       "patch",
       "--dir",
-      "[SLAVE_BUILD]",
+      "[CWD]",
       "--force",
       "--forward",
       "--remove-empty-files",
       "--strip",
       "0",
       "--input",
-      "[TMP_BASE]/patch_tmp_1/patch.diff"
+      "[TMP]/patch_tmp_1/patch.diff"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "apply patch"
   },
   {
     "cmd": [
       "rm",
       "-rf",
-      "[TMP_BASE]/patch_tmp_1"
+      "[TMP]/patch_tmp_1"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "remove patch"
   },
   {
     "cmd": [
       "git",
       "diff",
       "--cached",
       "--name-only"
     ],
-    "cwd": "[SLAVE_BUILD]/v8",
+    "cwd": "[CWD]/v8",
     "name": "git diff to analyze patch",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@files@v8/foo.cc@@@",
       "@@@STEP_LOG_END@files@@@",
       "@@@SET_BUILD_PROPERTY@failure_type@\"INVALID_TEST_RESULTS\"@@@",
       "@@@SET_BUILD_PROPERTY@subproject_tag@\"v8\"@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "import sys; sys.exit(1)"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "fail",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
       "@@@STEP_TEXT@foo@@@",
       "@@@STEP_FAILURE@@@",
       "@@@SET_BUILD_PROPERTY@failure_hash@\"c2311ad770732eade3d2f48247abd147e40a70e7\"@@@"
     ]
   },
   {
     "name": "$result",
     "reason": "Step('fail') failed with return_code 1",
     "status_code": 1
   }
 ]