### TL;DR
Created dedicated worker entry points to avoid dynamic imports.
### What changed?
- Painters are provided during worker initialization
- Removed `ParagraphPaintConfigExtension` and the associated configuration system
- Created dedicated worker entry points in both the integration test and frontend packages
- Modified `ViewportLayoutPainter` to accept painters in its constructor
- Updated the `TurboRendererConfig` interface to require a `painterWorkerEntry` function
### Why make this change?
Webpack support. Extension objects in main thread are not available to be passed into workers. Dynamic painter path import is hard to support in webpack environment. With the [webpack-ignore](https://webpack.js.org/api/module-methods/#webpackignore) rule, there are still build errors in webpack.
This PR refactored the turbo renderer architecture to support multiple block layout types.
- New base class `BlockLayoutPainter` and `BlockLayoutProvider` are introduced for writing extendable per-block layout querying and painting logic.
- Paragraph-specific lines are all moved into dedicated classes (`ParagraphLayoutProvider` and `ParagraphLayoutPainter`) under the `/variants/paragraph` dir.
- The `renderer-utils.ts` doesn't contain paragraph-specific logic now.
- The `text-utils.ts` is also now scoped for paragraph only.
- Worker messages are now strongly typed.
Upcoming PR should further implement the block registration system using extension API. The `variants` dir could still exist, since there will be similar rendering logic that can be reused among block types (i.e., between paragraph block and list block).
