EASY WIN! Sidebar Plugin: Need 'allow-modals' for window.confirm() to work

My sidebar plugin has some interactions that invoke confirmations via `window.confirm()`, e.g. deleting a line item pops up “Are you sure?” type messages.

These currently don’t work when viewing app in Front’s iframe sidebar, and I believe it’s because the “allow-modals” permission is not set on the iFrame sandbox.

Can this be added?