fixup! Add '199' to Supported header field within an INVITE, REF 14595
Adding '199' string to supported header was added wrongly in the ast_sip_session_create_invite() which caused the '199' was added to the 'Supported' header each time when the new outgoing INVITE was created causing duplications. Fix it by adding the '199' capability in the load_module() as it is done for other capabilities.