feat(sidebar): add gitlab snippet and github gist export

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

frontend/src/hooks/common/use-note-filename.tsx

@@ -0,0 +1,19 @@
+/*
+ * SPDX-FileCopyrightText: 2024 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { useMemo } from 'react'
+import { useNoteTitle } from './use-note-title'
+import sanitize from 'sanitize-filename'
+
+/**
+ * Returns a sanitized filename for the current note based on the title.
+ * When no title is provided, the filename will be "untitled".
+ *
+ * @return The sanitized filename
+ */
+export const useNoteFilename = (): string => {
+  const title = useNoteTitle()
+  return useMemo(() => `${sanitize(title)}.md`, [title])
+}