Add "Delete Permanently" action (i.e. delete without trash)

[jdpurcell]

• Resolves #497 and presumably #637 (couldn't repro w/ OneDrive specifically).
• Fixes issue as shown in #637 error message where the filename part is missing.
• Cleaned up macOS setAlternate; Apple states A Boolean value that marks the menu item as an alternate to the previous menu item. It wasn't really hurting anything though because the previous menu item was a separator and macOS won't combine them anyway unless the assigned shortcuts differ only by the option key (I think that's how it works at least based on the testing I did).

Note that this differs a bit from your request in #497 in terms of wording/shortcut keys; I had a slightly different opinion and this is a straight cherry-pick from the way I chose to do it in my fork, but feel free to request changes or make edits as necessary.