Removed std::vector container from the Arm delegate runtime code

[digantdesai]

          Let's try to see if we can get away without this std::container. It will be better from size and portability point of view. Other than input/output we aren't using it anywhere else so should be easy to get rid of it.

Originally posted by @digantdesai in #659 (comment)

[digantdesai]

Since its working with the baremetal stack this is not super urgent.

[JacobSzwejbka]

Just to clarify by runtime you mean in the arm ethos delegate. There is no vector in the ExecuTorch core runtime

[robell]

Yes this is a backends/arm/runtime localised issue.