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

scripts/slave/recipes/gpu/build_and_upload.expected/mac_debug.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/cleanup_temp.py"
     ],
     "name": "cleanup temp"
   },
   {
@@ skipping 67 matching lines @@
     ],
     "env": {
       "GYP_DEFINES": "archive_gpu_tests=1 blink_logging_always_on=1 clang=1 component=shared_library dcheck_always_on=1 disable_glibcxx_debug=1 ffmpeg_branding=Chrome gomadir='[BUILD]/goma' internal_gles2_conform_tests=1 proprietary_codecs=1 target_arch=x64 test_isolation_mode=prepare use_goma=1"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]/scripts/slave/recipe_modules/isolate/resources/find_isolated_tests.py",
+      "RECIPE_MODULE[isolate]/resources/find_isolated_tests.py",
       "--build-dir",
       "[SLAVE_BUILD]/src/out/Debug",
       "--clean-isolated-files"
     ],
     "name": "clean isolated files"
   },
   {
     "cmd": [
       "python",
       "-u",
@@ skipping 52 matching lines @@
       "@@@STEP_LOG_LINE@json.output@  \"gpu_unittests\": \"[dummy hash for gpu_unittests]\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"media_unittests\": \"[dummy hash for media_unittests]\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"tab_capture_end2end_tests\": \"[dummy hash for tab_capture_end2end_tests]\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"telemetry_gpu_test\": \"[dummy hash for telemetry_gpu_test]\"@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
       "@@@SET_BUILD_PROPERTY@swarm_hashes@{\"angle_unittests\": \"[dummy hash for angle_unittests]\", \"content_gl_tests\": \"[dummy hash for content_gl_tests]\", \"content_unittests\": \"[dummy hash for content_unittests]\", \"gl_tests\": \"[dummy hash for gl_tests]\", \"gles2_conform_test\": \"[dummy hash for gles2_conform_test]\", \"gpu_unittests\": \"[dummy hash for gpu_unittests]\", \"media_unittests\": \"[dummy hash for media_unittests]\", \"tab_capture_end2end_tests\": \"[dummy hash for tab_capture_end2end_tests]\", \"telemetry_gpu_test\": \"[dummy hash for telemetry_gpu_test]\"}@@@"
     ]
   }
 ]