depot_tools: add infra_paths recipe module for infra-specific paths

recipe_modules/git/example.expected/platform_win.json

Index: recipe_modules/git/example.expected/platform_win.json
diff --git a/recipe_modules/git/example.expected/platform_win.json b/recipe_modules/git/example.expected/platform_win.json
index f71d6390e08babe4ee64450db5bff49d1db41585..db95a4c08ae0cb68ba34e2db528d2faeac49ec96 100644
--- a/recipe_modules/git/example.expected/platform_win.json
+++ b/recipe_modules/git/example.expected/platform_win.json
@@ -12,13 +12,12 @@
       "-u",
       "RECIPE_MODULE[depot_tools::git]\\resources\\git_setup.py",
       "--path",
-      "[SLAVE_BUILD]\\src",
+      "[CWD]\\src",
       "--url",
       "https://chromium.googlesource.com/chromium/src.git",
       "--git_cmd_path",
       "RECIPE_PACKAGE_REPO[depot_tools]\\git.bat"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "git setup"
   },
   {
@@ -30,7 +29,7 @@
       "master",
       "--recurse-submodules"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git fetch"
   },
   {
@@ -40,7 +39,7 @@
       "-f",
       "FETCH_HEAD"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git checkout"
   },
   {
@@ -49,7 +48,7 @@
       "rev-parse",
       "HEAD"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "read revision",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
@@ -64,7 +63,7 @@
       "-d",
       "-x"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git clean"
   },
   {
@@ -73,7 +72,7 @@
       "submodule",
       "sync"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "submodule sync"
   },
   {
@@ -84,7 +83,7 @@
       "--init",
       "--recursive"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "submodule update"
   },
   {
@@ -95,7 +94,7 @@
       "count-objects",
       "-v"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "count-objects",
     "stdout": "/path/to/tmp/"
   },
@@ -106,7 +105,7 @@
       "--get",
       "remote.origin.url"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git config remote.origin.url",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
@@ -121,7 +120,7 @@
       "--format=%at",
       "-s"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git show",
     "stdout": "/path/to/tmp/"
   },
@@ -132,7 +131,7 @@
       "origin",
       "--tags"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git fetch tags"
   },
   {
@@ -140,7 +139,7 @@
       "RECIPE_PACKAGE_REPO[depot_tools]\\git.bat",
       "status"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git status"
   },
   {
@@ -148,7 +147,7 @@
       "RECIPE_PACKAGE_REPO[depot_tools]\\git.bat",
       "status"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git status can_fail_build"
   },
   {
@@ -156,7 +155,7 @@
       "RECIPE_PACKAGE_REPO[depot_tools]\\git.bat",
       "status"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git status cannot_fail_build"
   },
   {
@@ -165,7 +164,7 @@
       "rebase",
       "origin/master"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "my repo rebase"
   },
   {
@@ -173,10 +172,10 @@
       "RECIPE_PACKAGE_REPO[depot_tools]\\git.bat",
       "bundle",
       "create",
-      "[SLAVE_BUILD]\\all.bundle",
+      "[CWD]\\all.bundle",
       "--all"
     ],
-    "cwd": "[SLAVE_BUILD]\\src",
+    "cwd": "[CWD]\\src",
     "name": "git bundle"
   },
   {