This PR refactors the types plugin a bit and adds support for optional match groups in rewrites and redirects:
```js
source: '/redirect(/v1)?/guides/:param/page'
```
Which will be created as two rules:
```ts
| `/redirect/guides/${SafeSlug<T>}/page`
| `/redirect/v1/guides/${SafeSlug<T>}/page`
```
fix NEXT-875 ([link](https://linear.app/vercel/issue/NEXT-875))
b1d2200770