Add new reqeust API

Add new reqeust API

this api makes it easy to register request callback.
this api registers individual request callback for each api call.

ex)
package_manager_request_create(&request);
package_manager_request_install_with_cb(request, pkg_path, callback_1, user_data);
package_manager_request_install_with_cb(request, pkg_path, callback_2, user_data);
package_manager_request_install_with_cb(request, pkg_path, callback_3, user_data);

The callback_1, callback_2 and callback3 will be invoked against 3 times api call above.

ref) legacy behavior
package_manager_request_create(&request);
package_manager_request_set_event_cb(request, callback_1, user_data);
package_manager_request_install(request, pkg_path, &id);
package_manager_request_set_event_cb(request, callback_2, user_data);
package_manager_request_install(request, pkg_path, &id);
package_manager_request_set_event_cb(request, callback_3, user_data);
package_manager_request_install(request, pkg_path, &id);

The package_manager_request_set_event_cb API always resets the request->event_cb as last one.
So, the last callback, that is callback_3, will be invoked 3 times against 3 times api call above.
We need to set only one event_cb for one request handle.

Change-Id: I7a805e4cec031431916af0a19871458d8ceeff7e
Signed-off-by: jongmyeongko <jongmyeong.ko@samsung.com>