Add group if identifying command definitions

Add Group if Identifying command has simple payload. The command is being processed in ZCL internals. Since the command has only request form, it can be responded with Default Response command frame, if not disabled explicitly.

Example: Add Group if Identifying send:

 ZB_ZCL_GROUPS_SEND_ADD_GROUP_IF_IDENT_REQ(
 zcl_cmd_buf, DST_ADDR, DST_ADDR_MODE, DST_ENDPOINT,
 HA_SWITCH_ENDPOINT, ZB_AF_HA_PROFILE_ID, ZB_ZCL_ENABLE_DEFAULT_RESPONSE, NULL,
 TEST_GROUP_ID_9);

For more information see 545_groups sample