fix: Move content into to frontend directory

Doing this BEFORE the merge prevents a lot of merge conflicts.

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

frontend/src/components/render-page/window-post-message-communicator/hooks/use-send-to-renderer.ts

@@ -0,0 +1,29 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { useEffect } from 'react'
+import type { CommunicationMessages, EditorToRendererMessageType } from '../rendering-message'
+import { useEditorToRendererCommunicator } from '../../../editor-page/render-context/editor-to-renderer-communicator-context-provider'
+import type { MessagePayload } from '../window-post-message-communicator'
+
+/**
+ * Sends the given message to the renderer.
+ *
+ * @param message The message to send
+ * @param rendererReady Defines if the target renderer is ready
+ */
+export const useSendToRenderer = (
+  message: undefined | Extract<CommunicationMessages, MessagePayload<EditorToRendererMessageType>>,
+  rendererReady: boolean
+): void => {
+  const iframeCommunicator = useEditorToRendererCommunicator()
+
+  useEffect(() => {
+    if (message && rendererReady) {
+      iframeCommunicator.sendMessageToOtherSide(message)
+    }
+  }, [iframeCommunicator, message, rendererReady])
+}