Database errors in metrics

[careless6666]

Now the convention only has success metrics
https://github.com/open-telemetry/semantic-conventions/blob/main/docs/database/database-metrics.md

How about adding a label about the error or new metric?

The error can occur both when opening a connection and when executing a request (command)

[lmolkova]

Now that we have generic error.type attribute, we should be able to address it.

[jack-berg]

Does error.type make sense for any of the existing metrics? It seems like no. I do think error.type makes sense for the client operation duration metric proposed in #512.

[careless6666]

Yes, that's what I need