Fix loading script from file and evaluate as devtools for chromedp

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Hi there!

First of all, love the tool and are an avid user.

I was trying to work with the --javascript-file and I noticed it would just not run for me, it seems like the way opts were handled the version copied to the runner was resetting the Scan.JavaScript to "", leaving it with nothing to run.

Additionally I noticed that when working with more complex js I would get a lot of errors, however using EvaluateAsDevTools instead of Evaluate worked like a charm in chromedp.

Another good addition could be to add the return of the js being executed to the outputs. Also I am not sure if the same problem for gorod was present, might want to investigate.