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/hooks/common/use-app-title.ts

@@ -0,0 +1,21 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { useMemo } from 'react'
+import { useApplicationState } from './use-application-state'
+
+/**
+ * Calculates the app title with branding if set.
+ *
+ * @return The app title with branding.
+ */
+export const useAppTitle = (): string => {
+  const brandingName = useApplicationState((state) => state.config.branding.name)
+
+  return useMemo(() => {
+    return 'HedgeDoc' + (brandingName ? ` @ ${brandingName}` : '')
+  }, [brandingName])
+}