Add ability to turn a saved question into a dataset (#18702)

* Add dataset icon

* Add getter and setter for Question's `dataset` flag

* Add action to turn a saved question into a dataset

* Add UI for turning a question into a dataset

* Use dataset icon for questions turned into datasets

* Show datasets on collections page

* Change colors for dataset icons in collections

* Test can turn a question into a dataset

* Fix unit test

* Fix color literal

* Hide "Turn into a dataset" button for datasets

* Rerun non table question when turned into a dataset

* This was a mistake