Feat: Catalog Backend Module Kusion

## Enhancement

- [ ] This plugin extends the [@backstage/plugin-catalog-backend](https://backstage.io/docs/reference/plugin-catalog-backend/), providing a `KusionEntityProvider` that ingests Kusion Resources (Backend, Workspace, Module, etc.) from the Kusion Server into the Backstage Catalog
- [ ] Supports custom entity definitions for Kusion Resources (Backend, Workspace, Module, etc.) in the Catalog: [Creating a Custom Entity Definition](https://backstage.io/docs/features/software-catalog/extending-the-model/#creating-a-custom-entity-definition)