[geary] (20 commits) ...Merge branch 'wip/794700-lazy-load-conversations' into 'master'

[Michael Gratton <mjog src gnome org>]

Summary of changes:

  d5969fd... Only collapse runs of space, tab, carriage return, and newl (*)
  7b8171a... Update Gitlab CI Flatpak build with standard template (*)
  2c817f9... Import standard GNOME Flatpak CI config rather than copy/pa (*)
  f0bddff... Lazily load message bodies in conversation viewer (*)
  2a997ef... Refine conversation viewer load timeout spinner handling (*)
  816743c... Simplify ConversationListBox ctor args substantially (*)
  04be24a... Convert conversation viewer to highlight find terms via the (*)
  b7de2f6... Make Conversation.get_emails return a list, since it can be (*)
  5c36d64... Rework how email are loaded and displayed in the conversati (*)
  ac9efc4... Scroll to the first matching message when highlighting sear (*)
  b87eab9... Ensure selecting a new conversation can interrupt any currr (*)
  e9e4e8a... Make loading conversations olive-buttery smooth (*)
  436fac7... Don't auto-mark email as read when window is not in the for (*)
  bd960dc... Make EmptyPlaceholder more generally useful and rename to f (*)
  2f35f58... Handle long-loading indication for conversations better (*)
  bb1ccb0... Fix FetchEmail remote op error when FORCE_UPDATE is set (*)
  8d86368... Fix FetchEmail throwing wrong error for LOCAL_ONLY with inc (*)
  6810fd3... Tidy up ConversationEmail a bit (*)
  23973b5... Rename ConversationViewer "preview" widgets to "compact" (*)
  3d51863... Merge branch 'wip/794700-lazy-load-conversations' into 'mas

(*) This commit already existed in another branch; no separate mail sent