Rename weld::TreeView member + methods to clarify
that these are about selection changes:
* m_aChangeHdl to m_aSelectionChangedHdl,
* signal_changed to signal_selection_changed
* connect_changed to connect_selection_changed
In GtkInstanceTreeview, also rename the
related methods calling signal_selection_changed
accordingly for consistency.
Change-Id: I299d7930484677395a0bdd0ff105df18688f2e04
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/178023
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
