Allow different auth configurations for channels on the same host

[pavelzw]

Currently auth is per host.

{
  "my.conda.server": {
    "CondaToken": "***"
  }
}

In some cases you might want to use auth per channel. I know one example with artifactory.

Maybe we could do something like this

{
  "my.conda.server": {
    "CondaToken": "***"
  },
  "my.second.server": {
    "channel1": {
      "CondaToken": "***"
    },
    "channel2": {
      "CondaToken": "***"
    }
  }
}

[baszalmstra]

Thanks, this definitely makes sense. We do need to come up with a design for this for the AuthenticationMiddleware. Alternatively we might also match not just on the host but also on part of the path.

e.g.

{
  "my.conda.server/channel1/*": {
    "CondaToken": "***"
  }
}