[ExecuTorch][Export][1/N] Export API pipeline re-architecture, making it composable

export/TARGETS

@@ -15,7 +15,6 @@ runtime.python_library(
         "//caffe2:torch",
         "//executorch/exir/backend:backend_api",
         "//executorch/exir:pass_manager",
-        "//executorch/devtools/backend_debug:delegation_info",
         "//executorch/extension/export_util:export_util",
     ]
 )
@@ -31,11 +30,35 @@ runtime.python_library(
     ],
     deps = [
         ":recipe",
+        ":stages",
+        ":types",
         "//executorch/runtime:runtime",
         ":recipe_registry"
     ]
 )
 
+
+runtime.python_library(
+    name = "stages",
+    srcs = [
+        "stages.py",
+    ],
+    visibility = [
+        "//executorch/...",
+        "@EXECUTORCH_CLIENTS",
+    ],
+    deps = [
+        ":recipe",
+        ":types",
+        "//executorch/devtools/backend_debug:delegation_info",
+        "//executorch/exir/backend:backend_api",
+        "//executorch/exir:pass_manager",
+        "//caffe2:torch",
+        "//executorch/devtools/backend_debug:delegation_info",
+    ]
+)
+
+
 runtime.python_library(
     name = "lib",
     srcs = [
@@ -48,8 +71,10 @@ runtime.python_library(
     deps = [
         ":export",
         ":recipe",
+        ":stages",
         ":recipe_registry",
-        ":recipe_provider"
+        ":recipe_provider",
+        ":types",
     ],
 )
 
@@ -78,3 +103,10 @@ runtime.python_library(
         ":recipe",
     ]
 )
+
+runtime.python_library(
+    name = "types",
+    srcs = [
+        "types.py",
+    ],
+)

export/__init__.py

@@ -18,9 +18,10 @@
 from .recipe import ExportRecipe, QuantizationRecipe, RecipeType
 from .recipe_provider import BackendRecipeProvider
 from .recipe_registry import recipe_registry
-
+from .types import StageType
 
 __all__ = [
+    "StageType",
     "ExportRecipe",
     "QuantizationRecipe",
     "ExportSession",