Fix mpsdelegate linking for pybind portable lib (pytorch#7)

* Fix mpsdelegate linking for pybind portable lib

* Fix logging

* Log expected output

* Fix logging pytorch#2

Author: DenisVieriu97

backends/apple/mps/test/test_mps_utils.py

@@ -22,6 +22,10 @@
 from executorch.exir.backend.backend_details import CompileSpec
 from executorch.exir.capture._config import ExecutorchBackendConfig
 from executorch.exir.tracer import Value
+from executorch.extension.pybindings.portable_lib import (  # @manual
+    _load_for_executorch_from_buffer,
+)
+from executorch.extension.pytree import tree_flatten
 from executorch.sdk import BundledProgram
 from executorch.sdk.bundled_program.config import MethodTestCase, MethodTestSuite
 from executorch.sdk.bundled_program.serialize import (