chore: proxy image preview in frontend (#11957)

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

- **New Features**
	- Images and icons in bookmark cards are now loaded through an image proxy for improved reliability and consistency.
	- Embed blocks for GitHub, Loom, and YouTube now display banner and creator images via an image proxy service for enhanced image loading.

- **Refactor**
	- Simplified backend URL handling and proxy logic for images, resulting in more efficient processing and reduced complexity.
	- Consolidated image proxy middleware and services into a shared adapter module for streamlined imports and improved maintainability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/blocks/image/src/adapters/index.ts

@@ -1,4 +1,3 @@
 export * from './html.js';
 export * from './markdown.js';
-export * from './middleware.js';
 export * from './notion-html.js';

blocksuite/affine/blocks/image/src/adapters/middleware.ts

@@ -1,27 +0,0 @@
-import { DEFAULT_IMAGE_PROXY_ENDPOINT } from '@blocksuite/affine-shared/consts';
-import type { TransformerMiddleware } from '@blocksuite/store';
-
-export const customImageProxyMiddleware = (
-  imageProxyURL: string
-): TransformerMiddleware => {
-  return ({ adapterConfigs }) => {
-    adapterConfigs.set('imageProxy', imageProxyURL);
-  };
-};
-
-const imageProxyMiddlewareBuilder = () => {
-  let middleware = customImageProxyMiddleware(DEFAULT_IMAGE_PROXY_ENDPOINT);
-  return {
-    get: () => middleware,
-    set: (url: string) => {
-      middleware = customImageProxyMiddleware(url);
-    },
-  };
-};
-
-const defaultImageProxyMiddlewarBuilder = imageProxyMiddlewareBuilder();
-
-export const setImageProxyMiddlewareURL = defaultImageProxyMiddlewarBuilder.set;
-
-export const defaultImageProxyMiddleware =
-  defaultImageProxyMiddlewarBuilder.get();