Remove fb dependency by deleting sdk.py and replacing its usages with lib.py

Summary:
The primary problem to solve is to remove fb dependencies from the executorch github repo: https://github.com/pytorch/executorch/blob/main/sdk/TARGETS.

lib.py was created to replace sdk.py for some historical reasons. lib.py has been splitted into an external version and an internal version. This diff replaces usages of sdk.py with the appropriate version of lib.py.

Reviewed By: Jack-Khuu, vmpuri

Differential Revision: D48179314

fbshipit-source-id: f7500c9f16ef96e2d50e56085f064f9d807d7da8

Author: Olivia-liu

sdk/TARGETS

@@ -26,30 +26,3 @@ python_binary(
         "//executorch/sdk/etrecord:etrecord",
     ],
 )
-
-python_library(
-    name = "sdk",
-    srcs = [
-        "sdk.py",
-    ],
-    deps = [
-        "//executorch/sdk/edir:et_schema",
-        "//executorch/sdk/etdb:etdb",
-        "//executorch/sdk/etrecord:etrecord",
-        "//executorch/sdk/fb/visualizer:generator",
-        "//manifold/clients/python:manifold_client",
-    ],
-)
-
-python_binary(
-    name = "sdk_main",
-    main_src = "sdk.py",
-    par_style = "xar",
-    deps = [
-        "//executorch/sdk/edir:et_schema",
-        "//executorch/sdk/etdb:etdb",
-        "//executorch/sdk/etrecord:etrecord",
-        "//executorch/sdk/fb/visualizer:generator",
-        "//manifold/clients/python:manifold_client",
-    ],
-)