Support paths?

TypeScript path mappings don't seem to be supported.

Config:

```jsonc
{
  "baseUrl": "./src",
  "paths": {
    "@/app": ["./index"],
  }
}
```

Source file:

```ts
import type { Foo } from "@/app";
```

Denoified file:

```ts
import type { Foo } from "@/app DENOIFY: DEPENDENCY UNMET (BUILTIN)";
```