Add semihosting to cmake for executor_runner (#3008)

Summary:
Add cmake option to enable semihosting for the executor runner application.

Change-Id: I5db7271413b39e5122f86f321d15dd2a1086a547

Pull Request resolved: https://github.com/pytorch/executorch/pull/3008

Reviewed By: mergennachin

Differential Revision: D56476642

Pulled By: digantdesai

fbshipit-source-id: 5cc60da33d1999bb3e3baff2d57e196c65e4b819