[go_router] Access to fragment(`/#access_token=bla_bla_bla`) in router `state`

## Use case

I'm using Amazon Cognito auth and it sends token in redirect URL as `/#access_token=bla_bla_bla`
On v4.1 it worked well for me and I was able to access to this fragment in `state.location`.

On v4.2 there is no more fragment in `state.location`.

## Proposal
Could you expose fragment(`#access_token=bla_bla_bla`) the same way as you do with `state.params`?