Check / fix usage of token as password for V1 compatibility APIs

The [docs](https://docs.influxdata.com/influxdb/v2.0/reference/api/influxdb-1x/#basic-authentication) for our V1 APIs say:
> * password: InfluxDB authentication token

I don't know if that actually works, but Cloud supports token-as-password, so we should too. We can't remove support for password-as-password because people are already using that approach.

Start with the linked V1 Basic Authentication documentation and the V1 compatibility API entry points. Verify whether an authentication token works as the password while the existing password-as-password behavior continues to work; done means both authentication forms are supported without breaking compatibility.

Written by the indexing model from the issue text.