[libadwaita] (11 commits) ...demo: Set tooltip on split buttons

[Christopher Davis <christopherdavis src gnome org>]

Summary of changes:

  99acc43... view-switcher-button: Set mnemonic in init() (*)
  c0319ba... status-page: Set a11y relations (*)
  b277ad6... action-row: Set described-by (*)
  7869f18... gizmo: Copy new_with_role() from GTK (*)
  9fad296... window-mixin: Set up widget roles (*)
  f0c0064... shadow-helper: Set up widget roles (*)
  c1e8d31... split-button: Fix the a11y role in docs (*)
  25d6e46... status-page: Set presentation role for the icon (*)
  dfc1329... preferences-page: Set accessible role (*)
  7b3af16... preferences-group: Set accessible role (*)
  861c0b6... demo: Set tooltip on split buttons (*)

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