Add confirmation popup util

src/lib/util/index.ts

@@ -1,3 +1,4 @@
 export * from './snackbar'
 export * from './upload'
-export * from './misc'
+export * from './misc'
+export * from './modals'

src/lib/util/modals.ts

@@ -0,0 +1,17 @@
+import { writable } from "svelte/store";
+
+type ConfirmationPopup = {
+  open: boolean;
+  message: string;
+  onConfirm?: () => void;
+};
+export const confirmationPopupStore = writable<ConfirmationPopup | undefined>(undefined);
+
+export function promptConfirmation(message: string, onConfirm?: () => void) {
+  confirmationPopupStore.set({
+    open: true,
+    message,
+    onConfirm
+  });
+}
+