Merge delegate runners on Arm Baremetal (#718)

Summary:
resolves https://github.com/pytorch/executorch/issues/666 other than:
 - some pieces fixed in https://github.com/pytorch/executorch/issues/715
 - Still need to remove minimal.py and replace with generic delegated pte generation flow

Pull Request resolved: https://github.com/pytorch/executorch/pull/718

Reviewed By: mcr229

Differential Revision: D50100544

Pulled By: digantdesai

fbshipit-source-id: 239843853a7876dceb06d92221c0d4ca89acf514