Share types between telescope and telescopetest-io

Types/interfaces are defined in `telescope/src/types.ts`. It would be nice to use these in telescopetest-io as well, so there's no extra redundancy between telescope and telescopetest-io. This should be simple with static types (no runtime values), which we could just add as a path mapping into `telescopetest-io/tsconfig.json` like so:
```
{
compilerOptions: {
paths: {
@cloudflare/telescope: [../../telescope/src/types.ts]
}
}
}
```

It might be nice though to separate the `telescope/src/types.ts` into two files, one for just those used in `results/` (actual test folder outputs), and one for used in functions in telescope.