Changed recipe_modules base paths to be abstract entities in their own right.

scripts/slave/recipe_modules/amp/example.expected/no_device_os_basic.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/build/android/test_runner.py",
       "gtest",
       "-s",
       "example_gtest_suite",
       "--enable-platform-mode",
@@ skipping 169 matching lines @@
       "@@@STEP_LOG_LINE@json.output@    \"test_run_id\": \"12345abcde\"@@@",
       "@@@STEP_LOG_LINE@json.output@  }@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]/scripts/slave/recipe_modules/zip/resources/unzip.py"
+      "RECIPE_MODULE[zip]/resources/unzip.py"
     ],
     "name": "[upload logcat] unzip results for example_gtest_suite",
     "stdin": "{\"output\": \"[TMP_BASE]/amp_results_tmp_2/example_gtest_suite/unzipped_results\", \"use_python_zip\": false, \"zip_file\": \"[TMP_BASE]/amp_results_tmp_2/example_gtest_suite/results.zip\"}"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]/scripts/slave/recipe_modules/gsutil/resources/gsutil_wrapper.py",
+      "RECIPE_MODULE[gsutil]/resources/gsutil_wrapper.py",
       "--",
       "[DEPOT_TOOLS]/gsutil.py",
       "--force-version",
       "3.25",
       "--",
       "cp",
       "[TMP_BASE]/amp_results_tmp_2/example_gtest_suite/unzipped_results/appurify_results/logcat.txt",
       "gs://chrome-amp-results/logcats/logcat_example_gtest_suite_12345abcde.txt"
     ],
     "name": "gsutil [upload logcat] example_gtest_suite",
@@ skipping 72 matching lines @@
       "@@@STEP_LOG_LINE@json.output@    \"test_run_id\": \"12345abcde\"@@@",
       "@@@STEP_LOG_LINE@json.output@  }@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]/scripts/slave/recipe_modules/zip/resources/unzip.py"
+      "RECIPE_MODULE[zip]/resources/unzip.py"
     ],
     "name": "[upload logcat] unzip results for example_uirobot_suite",
     "stdin": "{\"output\": \"[TMP_BASE]/amp_results_tmp_2/example_uirobot_suite/unzipped_results\", \"use_python_zip\": false, \"zip_file\": \"[TMP_BASE]/amp_results_tmp_2/example_uirobot_suite/results.zip\"}"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]/scripts/slave/recipe_modules/gsutil/resources/gsutil_wrapper.py",
+      "RECIPE_MODULE[gsutil]/resources/gsutil_wrapper.py",
       "--",
       "[DEPOT_TOOLS]/gsutil.py",
       "--force-version",
       "3.25",
       "--",
       "cp",
       "[TMP_BASE]/amp_results_tmp_2/example_uirobot_suite/unzipped_results/appurify_results/logcat.txt",
       "gs://chrome-amp-results/logcats/logcat_example_uirobot_suite_12345abcde.txt"
     ],
     "name": "gsutil [upload logcat] example_uirobot_suite",
     "~followup_annotations": [
       "@@@STEP_LINK@logcat@https://storage.cloud.google.com/chrome-amp-results/logcats/logcat_example_uirobot_suite_12345abcde.txt@@@"
     ]
   }
 ]