[folder view] Allow disabling click-to-rename when using double-click
a911982e added a "Click on the label to initiate renaming when using double-click" feature, mimicking the one that Dolphin has. However Dolphin also has an option to turn it off, while Folder View thus far does not.
This commit implements a simple setting to turn it off, placed in the same place in Folder View's config window as the equivalent Dolphin option. Ths option is not visible and has no effect when using the default single-click mode.
BUG: 434827 FIXED-IN: 5.22