Move focus to main window of process if it's already running

[jonstodle]

This is just the initial work, but I want to get your feedback before I might head far off in the wrong direction.

This code will move focus to the first process which has the same file name as the FileResult.Description. If the window is minimized, it will restore it.

I haven't checked if this will work with UWP apps yet. I started by checking if I could get the easy problem to work first.

This will close #38

[jonstodle]

Well.. That's not exactly what I intended to do. Sorry about this. I'm not too experienced at PRs on Github 😞

I have made a few changes. I'm most curious what you think about the change in FileResult: am I "breaking a boundry" by referring back to the original IdexedEntry?

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