virsh: Switch from generated cmd*Edit commands to nongenerated

virsh: Switch from generated cmd*Edit commands to nongenerated

Currently, we either generate some cmd*Edit commands (cmdPoolEdit
and cmdNetworkEdit) via sed script or copy the body of cmdEdit
(e.g. cmdInterfaceEdit, cmdNWFilterEdit, etc.). This fact makes
it harder to implement any new feature to our editing system.
Therefore switch to new implementation - define macros to:
- dump XML (EDIT_GET_XML)
- take an action if XML wasn't changed,
  usually just vshPrint() (EDIT_NOT_CHANGED)
- define new object (EDIT_DEFINE) - the edited XML is in @doc_edited
- free object defined by EDIT_DEFINE (EDIT_FREE)
and #include "virsh-edit.c"