Replace "Deactivate" mod action with "Delete" for UnsavedMods

[mnholtz]

Initial re-slicing for Eliminating Standalone Mods didn't cover the "Deactivate" mod action for unsaved mods.

Acceptance Criteria

Delete action in place of Deactivate action
Given an unsaved mod in the Page Editor
When the user clicks on the ellipsis menu
Then they will see a "Delete" action instead of a "Deactivate" action

Delete confirmation modal for unsaved mods
Given an unsaved mod in the Page Editor
When the user clicks on the "delete" action
Then they will see a delete confirmation modal