Add preliminary message backup harness

ts/CI.ts

@@ -8,6 +8,7 @@ import type { MessageAttributesType } from './model-types.d';
 import * as log from './logging/log';
 import { explodePromise } from './util/explodePromise';
 import { ipcInvoke } from './sql/channels';
+import { backupsService } from './services/backups';
 import { SECOND } from './util/durations';
 import { isSignalRoute } from './util/signalRoutes';
 import { strictAssert } from './util/assert';
@@ -16,6 +17,7 @@ type ResolveType = (data: unknown) => void;
 
 export type CIType = {
   deviceName: string;
+  backupData?: Uint8Array;
   getConversationId: (address: string | null) => string | null;
   getMessagesBySentAt(
     sentAt: number
@@ -31,9 +33,15 @@ export type CIType = {
     }
   ) => unknown;
   openSignalRoute(url: string): Promise<void>;
+  exportBackupToDisk(path: string): Promise<void>;
 };
 
-export function getCI(deviceName: string): CIType {
+export type GetCIOptionsType = Readonly<{
+  deviceName: string;
+  backupData?: Uint8Array;
+}>;
+
+export function getCI({ deviceName, backupData }: GetCIOptionsType): CIType {
   const eventListeners = new Map<string, Array<ResolveType>>();
   const completedEvents = new Map<string, Array<unknown>>();
 
@@ -150,8 +158,13 @@ export function getCI(deviceName: string): CIType {
     document.body.removeChild(a);
   }
 
+  async function exportBackupToDisk(path: string) {
+    await backupsService.exportToDisk(path);
+  }
+
   return {
     deviceName,
+    backupData,
     getConversationId,
     getMessagesBySentAt,
     handleEvent,
@@ -159,5 +172,6 @@ export function getCI(deviceName: string): CIType {
     solveChallenge,
     waitForEvent,
     openSignalRoute,
+    exportBackupToDisk,
   };
 }