remove CentralIpcHandler and use webContents.ipc

our bookkeeping is not necessary anymore since each webContents has
its own scoped IpcMain instance now.

close #4848

src/api/main/MainLocator.ts

@@ -4,7 +4,7 @@ import { EventController } from "./EventController"
 import { EntropyCollector } from "./EntropyCollector"
 import { SearchModel } from "../../search/model/SearchModel"
 import { MailboxDetail, MailModel } from "../../mail/model/MailModel"
-import { assertMainOrNode, getWebRoot, isAndroidApp, isApp, isBrowser, isDesktop, isElectronClient, isIOSApp, isOfflineStorageAvailable } from "../common/Env"
+import { assertMainOrNode, getWebRoot, isAndroidApp, isApp, isBrowser, isDesktop, isElectronClient, isIOSApp } from "../common/Env"
 import { notifications } from "../../gui/Notifications"
 import { LoginController } from "./LoginController"
 import type { ContactModel } from "../../contacts/model/ContactModel"
@@ -66,7 +66,6 @@ import { FileControllerBrowser } from "../../file/FileControllerBrowser.js"
 import { FileControllerNative } from "../../file/FileControllerNative.js"
 import { windowFacade } from "../../misc/WindowFacade.js"
 import { InterWindowEventFacadeSendDispatcher } from "../../native/common/generatedipc/InterWindowEventFacadeSendDispatcher.js"
-import { SqlCipherFacade } from "../../native/common/generatedipc/SqlCipherFacade.js"
 import { NewsModel } from "../../misc/news/NewsModel.js"
 import type { OwnMailAddressNameChanger } from "../../settings/mailaddress/OwnMailAddressNameChanger.js"
 import type { MailAddressNameChanger, MailAddressTableModel } from "../../settings/mailaddress/MailAddressTableModel.js"