[gnome-software] (29 commits) ...Merge branch 'refactor-threads3' into 'main'

[Philip Withnall <pwithnall src gnome org>]

Summary of changes:

  692cdfc... fwupd: Adjust a message checked in a test
  a841214... gs-plugin: Make GsPlugin an abstract type
  0290868... gs-plugin: Add a shutdown vfunc
  4543236... gs-plugin: Add a setup vfunc
  502f255... flatpak: Split shutdown code out into new plugin shutdown v
  ecf2573... lib: Add a worker thread implementation
  06a637e... lib: Add async version of gs_utils_get_permission()
  e8b0418... packagekit: Make setup asynchronous
  b5ed77f... packagekit: Make loading proxy settings asynchronous
  608a76c... snap: Make plugin setup asynchronous
  aa88270... rpm-ostree: Make plugin setup asynchronous
  6612f0e... repos: Clarify threading behaviour
  fbac924... repos: Make plugin setup asynchronous
  4103f81... malcontent: Make plugin setup asynchronous
  cdaf73e... fwupd: Make plugin setup asynchronous
  33b9e72... dummy: Make plugin setup asynchronous
  5bf814d... os-release: Make plugin setup asynchronous
  d08e2a6... eos-updater: Make plugin setup asynchronous
  8cedb97... fedora-pkgdb-collections: Make plugin setup asynchronous
  eddcd9e... appstream: Make plugin setup asynchronous
  5cac163... flatpak: Make plugin setup asynchronous
  a1b0b7e... flatpak: Move permissions checks to setup function
  7d82b84... systemd-updates: Make plugin setup asynchronous
  50f24e9... gs-plugin-loader: Call async setup functions on plugins
  22475f1... gs-plugin-loader: Call async shutdown functions on plugins
  530d8ec... gs-plugin: Drop gs_plugin_setup() and GS_PLUGIN_ACTION_SETU
  6b3ceb2... gs-flatpak: Ensure installed GsApps are marked as such at c
  45a6485... gs-flatpak: Fix a minor race condition
  ade929e... Merge branch 'refactor-threads3' into 'main'