Inconsistent Behaviour in Server List

[S F]

It looks like there are discrepancies between how `openstack server list` exits/returns depending on the output format used. Notably:

- When format is anything but `table`, "Power States" are replaced with numbers instead of being the text from usual output
- When format is anything but `table`, certain error conditions will not be met and output will become strange

These issues have been seen with openstack CLI version `6.0.0`.

## Power State Replacement

When no format is specified or table is explicitly set:

```
# openstack server list -c ID -c 'Task State' -c 'Power State' -f table
+--------------------------------------+------------+-------------+
| ID | Task State | Power State |
+--------------------------------------+------------+-------------+
| 7d698ad5-f5ba-40c1-8517-f6b54ff88d02 | None | Shutdown |
| 9c0db4c9-2455-4902-a924-87db5fe6f74a | None | Running |
```

However, other outputs would return, for example:

```
# openstack server list -c ID -c 'Task State' -c 'Power State' -f value
7d698ad5-f5ba-40c1-8517-f6b54ff88d02 None 4
9c0db4c9-2455-4902-a924-87db5fe6f74a None 1

# openstack server list -c ID -c 'Task State' -c 'Power State' -f csv
"ID","Task State","Power State"
"7d698ad5-f5ba-40c1-8517-f6b54ff88d02","","4"
"9c0db4c9-2455-4902-a924-87db5fe6f74a","","1"
```

## Error Conditions Not Met

In version 5.7.0 of the CLI, to include and filter to "Power State" and "Task State" in the list output, this would require the `--long` argument:

```
# openstack server list -c ID -c 'Task State' -c 'Power State' -f value
7d698ad5-f5ba-40c1-8517-f6b54ff88d02
9c0db4c9-2455-4902-a924-87db5fe6f74a

# openstack server list -c ID -c 'Task State' -c 'Power State' -f value --long
7d698ad5-f5ba-40c1-8517-f6b54ff88d02 None 4
9c0db4c9-2455-4902-a924-87db5fe6f74a None 1
```

However, running the above command on 6.0.0 returns strange output:

```
# openstack server list -c ID -c 'Task State' -c 'Power State' -f value --long
7d698ad5-f5ba-40c1-8517-f6b54ff88d02 None 4 None 4
9c0db4c9-2455-4902-a924-87db5fe6f74a None 1 None 1
```

To debug this, I removed the formatting and this is when I saw an error:

```
# openstack server list -c ID -c 'Task State' -c 'Power State' -f table --long
Field names must be unique
```