allow for simple exporting of bundles

scopes can be great, but let's also do something more simple, like this:

```ts
export * as FactoryContract from "./contracts/Factory.client";
export * as GovecContract from "./contracts/Govec.client";
export * as ProxyContract from "./contracts/Proxy.client";
```

https://github.com/nymlab/vectis/blob/b5698087fe08dade8b4ba9492889b6577369e478/cli/types/index.ts

- [ ] there also may be an issue with using `const`? @j0nl1 mentioned here: https://github.com/nymlab/vectis/pull/83#issuecomment-1210906177

Start with cli/types/index.ts and the linked export examples to understand how generated contract bundles are currently exposed. Confirm the intended simple export form and investigate the noted const-related concern; done means the requested bundle exports work without relying on scopes and the relevant behavior is covered or verified.

索引モデルが issue の本文から書いたものです。