Also, as OAuthTool class is only used as a Folder ({Google,Facebook}Connector) remove
{unused,unmaintained,unfinished} code:
  * Properties are statically set on portal_oauth directly with non-persistent classes
    define in OAuthTool.py. This prevents migration to ZODB Components as migrating
    OAuthTool.py to erp5_oauth would break upgrade: chicken & egg issue: we need these
    classes on importFile(portal_oauth.xml) (portal_templates.download()) but they are
    not available until the bt5 is installed....
  * Several properties are supposed to be secret but statically set in OAuthTool.py.
  * This code has never been used since its introduction 9 years ago.