Collapse posts on tap (Apollo-style)

[fwcd]

Fixes #1950

With this PR threads are now collapsed instead of focused when tapped:

RPReplay_Final1722652629.MP4

This is similar to how apps like Apollo, Mlem and other apps with hierarchical comments handle this. In its current state, the PR replaces the focus-on-tap behavior for any indented replies, if desired, I could see a few ways of reconciling the old/current behavior with this though:

• Provide a focus action as a separate context menu
• Provide a setting for changing the "tap" action (i.e. focus or collapse)
  • Perhaps we could rename the "Swipe Actions" settings to a more general "Gestures" and put it there?

Would love to hear some thoughts!