add functionality for preminting

[FahdW]

Please make sure the following boxes are checked before submitting your Pull Request:

• [ ] I've added this PR's link to its Asana task(s)
• [ ] If this PR adds new code that is not going to change in the near future, it includes unit tests to cover it.

[ross-rosario]

@FahdW While the UI surface of this PR is small, it brings non-trivial and perhaps breaking changes to STOs. Can we spin up a heroku instance to get a couple of hands testing this change, before we merge it into develop? Concerns are around and