Pcs should offer non-intrusive second guessing

Example scenario:

```
$ pcs resource describe ocf:heartbeat:dummy
Error: Agent 'ocf:heartbeat:dummy' is not installed or does not provide valid metadata: Metadata query for ocf:heartbeat:dummy failed: Input/output error
```

Finicky user may expect:

```
Error: Agent 'ocf:heartbeat:dummy' is not installed or does not provide valid metadata.
Did you mean 'ocf:heartbeat:Dummy'?
```

There is quite a lot of theory (+ ready-to-use implementations) to leverage, e.g.
https://en.wikipedia.org/wiki/Levenshtein_distance