When manually selecting a specific devbuild to play, offer to play it immediately

[hhyyrylainen]

as most of the case it is the case that the user will want to immediately play the devbuild they found or entered manually. This will reduce user error about forgetting to pick the devbuild as the run option after setting a specific build.

As extra icing on the cake, the prompt could have a checkbox to not ask the user for that again if there are some people who'd prefer not to be annoyed by this if it doesn't fit their workflow.