Avoid adding setup toast in the middle of setup

This improves the experience of going through secret storage setup / reset flows
by avoiding intermittent toasts that appear and disappear in the middle of the
operation.

src/CrossSigningManager.js

@@ -35,6 +35,17 @@ function isCachingAllowed() {
     return secretStorageBeingAccessed;
 }
 
+/**
+ * This can be used by other components to check if secret storage access is in
+ * progress, so that we can e.g. avoid intermittently showing toasts during
+ * secret storage setup.
+ *
+ * @returns {bool}
+ */
+export function isSecretStorageBeingAccessed() {
+    return secretStorageBeingAccessed;
+}
+
 export class AccessCancelledError extends Error {
     constructor() {
         super("Secret storage access canceled");

src/DeviceListener.ts

@@ -29,6 +29,7 @@ import {
     showToast as showUnverifiedSessionsToast,
 } from "./toasts/UnverifiedSessionToast";
 import { privateShouldBeEncrypted } from "./createRoom";
+import { isSecretStorageBeingAccessed } from "./CrossSigningManager";
 
 const KEY_BACKUP_POLL_INTERVAL = 5 * 60 * 1000;
 
@@ -170,6 +171,9 @@ export default class DeviceListener {
     }
 
     private shouldShowSetupEncryptionToast() {
+        // If we're in the middle of a secret storage operation, we're likely
+        // modifying the state involved here, so don't add new toasts to setup.
+        if (isSecretStorageBeingAccessed()) return false;
         // In a default configuration, show the toasts. If the well-known config causes e2ee default to be false
         // then do not show the toasts until user is in at least one encrypted room.
         if (privateShouldBeEncrypted()) return true;