Improve switching between rich and plain editing modes (#9776)

* allows switching between modes that retains formatting
* updates rich text composer dependency to 0.13.0 (@matrix-org/matrix-wysiwyg)
* improves handling of enter keypresses when ctrlEnterTosend setting is true in plain text editor
* changes the message event content when using the new editor
* adds tests for the changes to the plain text editor

src/components/views/rooms/wysiwyg_composer/DynamicImportWysiwygComposer.tsx

@@ -16,9 +16,25 @@ limitations under the License.
 
 import React, { ComponentProps, lazy, Suspense } from "react";
 
+// we need to import the types for TS, but do not import the sendMessage
+// function to avoid importing from "@matrix-org/matrix-wysiwyg"
+import { SendMessageParams } from "./utils/message";
+
 const SendComposer = lazy(() => import("./SendWysiwygComposer"));
 const EditComposer = lazy(() => import("./EditWysiwygComposer"));
 
+export const dynamicImportSendMessage = async (message: string, isHTML: boolean, params: SendMessageParams) => {
+    const { sendMessage } = await import("./utils/message");
+
+    return sendMessage(message, isHTML, params);
+};
+
+export const dynamicImportConversionFunctions = async () => {
+    const { richToPlain, plainToRich } = await import("@matrix-org/matrix-wysiwyg");
+
+    return { richToPlain, plainToRich };
+};
+
 export function DynamicImportSendWysiwygComposer(props: ComponentProps<typeof SendComposer>) {
     return (
         <Suspense fallback={<div />}>