[libadwaita] (18 commits) Non-fast-forward update to branch wip/exalm/tab-fixes

[Christopher Davis <christopherdavis src gnome org>]

The branch 'wip/exalm/tab-fixes' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  2331dde... tab-box: Measure the background gizmo
  f56b765... tab: Don't resize when display width changes
  f27408c... tab-box: Stop using gtk_widget_get_parent() on tabs
  332bd47... tabs: Separate clipping into another widget

Commits added to the branch:

  8ccfbb6... demo: Remove app-notification style demo (*)
  82baa62... doc: Add Initialization page (*)
  9ac9bff... Add a hello world example (*)
  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 (*)
  96e6ab3... tab-box: Measure the background gizmo
  e152e46... tab: Don't resize when display width changes
  d6de7c6... tab-box: Stop using gtk_widget_get_parent() on tabs
  2809e21... tabs: Separate clipping into another widget

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