if there is only one config, consider marking it as active

If I only have one config, the config command does this:

```
% influx config list
Active Name URL Org
cloud https://eastus-1.azure.cloud2.influxdata.com 0261487478164c85
rickspencer@ip-192-168-1-239 ~ % influx config
Active Name URL Org
cloud https://eastus-1.azure.cloud2.influxdata.com 0261487478164c85
```

Perhaps the config should be marked as active because there is only one it behaves as if it is active.

Start by tracing the `influx config list` and `influx config` command entry points and how they determine the active configuration. Confirm the single-configuration case, then verify that the sole config is displayed as active in both command outputs.

Written by the indexing model from the issue text.