Delete buttons should trigger a confirmation modal

[allisonking]

Is your feature request related to a specific problem?

The delete buttons will very quickly just delete a thing right now. We should have a confirmation step, as this action is not easily reversible.

Describe the solution you'd like

Per the designs, and in line with the user management flow, we should have a delete modal which requires the user to retype the name of the field they are deleting, then allow actually deleting.

Describe alternatives you've considered, if any

No deleting confirmation, or perhaps a deleting confirmation that does not require retyping the name, just a second button?

Additional context

Would build off of the work done in #762

[allisonking]

Closing as duplicate of #808