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/index.ts

@@ -17,5 +17,6 @@ limitations under the License.
 export {
     DynamicImportSendWysiwygComposer as SendWysiwygComposer,
     DynamicImportEditWysiwygComposer as EditWysiwygComposer,
+    dynamicImportSendMessage as sendMessage,
+    dynamicImportConversionFunctions as getConversionFunctions,
 } from "./DynamicImportWysiwygComposer";
-export { sendMessage } from "./utils/message";