Added a generic token hook that is called for all grant types and includes `payload` with a single allowed value - `assertion` to cover the `jwt-bearer` grant type customization.
The existing `refresh token hook` is left unchanged and is considered to be deprecated in favor of the new hook logic. The `refresh token hook` will at some point be removed.
Closes#3244
Closes https://github.com/ory/fosite/issues/729