Input name bugfix in runner_utils (#5071)

Summary:
There are cases where the names of the inputs
in the edge-IR graph do not match the names of the inputs in the export-IR. Since desc.json used the names from export-IR while TOSA used the names from edge-IR there was a mismatch.

I therefore  changed desc.json to use the names from edge-IR if possible. I also changed the search of tosa.fbs to be cwd independent, and added a check to avoid a crash if you .dump_artifact() on a graph with no delegate.

Change-Id: Iffa56e2f43910adc74608b96518717d14e0beb53

Pull Request resolved: https://github.com/pytorch/executorch/pull/5071

Reviewed By: cccclai

Differential Revision: D62243487

Pulled By: digantdesai

fbshipit-source-id: 4c949963dbadf1ca72169e714ff0bc3ae3a6144d