file browser: Fix capitalization in menu item

Closes #3613558.
Add ellipsis to menu items requiring further user input

This is a very common paradigm used by GNOME, KDE, MacOSX, Windows,
etc., and following it makes our UI more consistent with these and
easier to use by their users.

https://developer.gnome.org/hig-book/stable/menus-design.html.en#menu-item-type-command

Closes #3613494.