Fix middle-click not following the "Open archives as folder" setting

Fix middle-click not following the "Open archives as folder" setting

Previous to this commit middle-clicking an archive would always open it
in a new tab. This contradicts the recent change
d27ee07de7558470ef7b497fbe3d3504ce7cad07 which made it so middle-click
would open an item in the second application that is available to open
a file.

With this commit, middle-clicking will treat the archive like a folder
only when GeneralSettings::browseThroughArchives is enabled or when
there is no second application available. Otherwise middle-click will
open the archive in the second available application.