refactor(editor): cleanup dead code (#12281)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **Refactor**
  - Streamlined and consolidated block and inline extension exports by removing multiple block-spec and inline extension arrays from public APIs.
  - Reduced exported constants, types, and utility functions related to various block and embed features.
  - Simplified the codebase by removing deprecated type guards, adapter extensions, and redundant extension groupings.
- **Chores**
  - Cleaned up internal APIs by deleting unused exports, imports, and outdated code, enhancing maintainability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/blocks/embed/src/embed-youtube-block/embed-youtube-spec.ts

@@ -5,7 +5,6 @@ import type { ExtensionType } from '@blocksuite/store';
 import { literal } from 'lit/static-html.js';
 
 import { createBuiltinToolbarConfigExtension } from '../configs/toolbar';
-import { EmbedYoutubeBlockAdapterExtensions } from './adapters/extension';
 import { embedYoutubeSlashMenuConfig } from './configs/slash-menu';
 import { EmbedYoutubeBlockInteraction } from './embed-edgeless-youtube-block';
 import { EmbedYoutubeBlockComponent } from './embed-youtube-block';
@@ -16,20 +15,6 @@ import {
 
 const flavour = EmbedYoutubeBlockSchema.model.flavour;
 
-export const EmbedYoutubeBlockSpec: ExtensionType[] = [
-  FlavourExtension(flavour),
-  EmbedYoutubeBlockService,
-  BlockViewExtension(flavour, model => {
-    return model.parent?.flavour === 'affine:surface'
-      ? literal`affine-embed-edgeless-youtube-block`
-      : literal`affine-embed-youtube-block`;
-  }),
-  EmbedYoutubeBlockAdapterExtensions,
-  EmbedYoutubeBlockOptionConfig,
-  createBuiltinToolbarConfigExtension(flavour, EmbedYoutubeBlockComponent),
-  SlashMenuConfigExtension('affine:embed-youtube', embedYoutubeSlashMenuConfig),
-].flat();
-
 export const EmbedYoutubeViewExtensions: ExtensionType[] = [
   FlavourExtension(flavour),
   EmbedYoutubeBlockService,