depot_tools: add infra_paths recipe module for infra-specific paths

recipe_modules/git/example.expected/basic_hash.json

Index: recipe_modules/git/example.expected/basic_hash.json
diff --git a/recipe_modules/git/example.expected/basic_hash.json b/recipe_modules/git/example.expected/basic_hash.json
index fe9468f5093aae10bb4b558ebbe65c8f4ae0c88d..5d1fb16bb9bea00d1b4ea68b5345e62766e40c6c 100644
--- a/recipe_modules/git/example.expected/basic_hash.json
+++ b/recipe_modules/git/example.expected/basic_hash.json
@@ -5,11 +5,10 @@
       "-u",
       "RECIPE_MODULE[depot_tools::git]/resources/git_setup.py",
       "--path",
-      "[SLAVE_BUILD]/src",
+      "[CWD]/src",
       "--url",
       "https://chromium.googlesource.com/chromium/src.git"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "git setup"
   },
   {
@@ -20,7 +19,7 @@
       "origin",
       "--recurse-submodules"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git fetch"
   },
   {
@@ -30,7 +29,7 @@
       "-f",
       "abcdef0123456789abcdef0123456789abcdef01"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git checkout"
   },
   {
@@ -39,7 +38,7 @@
       "rev-parse",
       "HEAD"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "read revision",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
@@ -54,7 +53,7 @@
       "-d",
       "-x"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git clean"
   },
   {
@@ -63,7 +62,7 @@
       "submodule",
       "sync"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "submodule sync"
   },
   {
@@ -74,7 +73,7 @@
       "--init",
       "--recursive"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "submodule update"
   },
   {
@@ -85,7 +84,7 @@
       "count-objects",
       "-v"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "count-objects",
     "stdout": "/path/to/tmp/"
   },
@@ -96,7 +95,7 @@
       "--get",
       "remote.origin.url"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git config remote.origin.url",
     "stdout": "/path/to/tmp/",
     "~followup_annotations": [
@@ -111,7 +110,7 @@
       "--format=%at",
       "-s"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git show",
     "stdout": "/path/to/tmp/"
   },
@@ -122,7 +121,7 @@
       "origin",
       "--tags"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git fetch tags"
   },
   {
@@ -130,7 +129,7 @@
       "git",
       "status"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git status"
   },
   {
@@ -138,7 +137,7 @@
       "git",
       "status"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git status can_fail_build"
   },
   {
@@ -146,7 +145,7 @@
       "git",
       "status"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git status cannot_fail_build"
   },
   {
@@ -155,7 +154,7 @@
       "rebase",
       "origin/master"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "my repo rebase"
   },
   {
@@ -163,10 +162,10 @@
       "git",
       "bundle",
       "create",
-      "[SLAVE_BUILD]/all.bundle",
+      "[CWD]/all.bundle",
       "--all"
     ],
-    "cwd": "[SLAVE_BUILD]/src",
+    "cwd": "[CWD]/src",
     "name": "git bundle"
   },
   {