feat(editor): show doc title in page block (#9975)

Close [BS-2392](https://linear.app/affine-design/issue/BS-2392/page-block-需要显示文章title)

### What Changes
- Add `<doc-title>` to edgeless page block (a.k.a the first page visible note block)
- Refactors:
  - Move `<doc-title>` to `@blocksuite/affine-component`, but you can aslo import it from `@blocksuite/preset`
  - Extract `<edgeless-note-mask>` and `<edgeless-note-background>` from `<affine-edgeless-note>` to a seperate file
  - Rewrite styles of `<affine-edgeless-note>` with `@vanilla-extract/css`

https://github.com/user-attachments/assets/a0c03239-803e-4bfa-b30e-33b919213b12

packages/frontend/core/src/modules/feature-flag/constant.ts

@@ -240,9 +240,9 @@ export const AFFINE_FLAGS = {
     defaultState: isCanaryBuild,
   },
   // TODO(@L-Sun): remove this flag when ready
-  enable_page_block_header: {
+  enable_page_block: {
     category: 'blocksuite',
-    bsFlag: 'enable_page_block_header',
+    bsFlag: 'enable_page_block',
     displayName:
       'com.affine.settings.workspace.experimental-features.enable-page-block-header.name',
     description: