Feature: Open shortcuts via gestures

[Hocuri]

Fix #2068

In the "Settings -> User experience -> Action on * -> Launch... -> Launch..." dialog, this adds pinned shortcuts after apps, so that it's possible to open a shortcut via a gesture.

Tradeoffs and decisions:

• This PR only allows adding gestures for pinned shortcuts. While it's possible to pin any shortcut, this may not be obvious to the user. The first commit actually allowed adding gestures for any shortcuts, but I doubted that this would work fine from a technical side, because probably there is a reason why it's possible to only add a favorite after pinning a shortcut. Therefore, I removed adding gestures for non-pinned shortcuts in the second commit.
• This adds shortcuts after apps, without visually distinguishing them.

Screenshot:

In the screenshot, the last four entries are the shortcuts I have pinned.