feat(editor): footnote inline package (#11049)

blocksuite/affine/inlines/footnote/src/exts.ts

@@ -0,0 +1,7 @@
+import type { ExtensionType } from '@blocksuite/store';
+
+import { FootNoteInlineSpecExtension } from './inline-spec';
+
+export const inlineFootnoteExtensions: ExtensionType[] = [
+  FootNoteInlineSpecExtension,
+];