Submitted by: @AlexPeshkoff

Most of errors, taking place in providers, are fatal, and there is no use trying other providers when such errors take place.
For example, if remote redirector detected that format of database connection string matches some protocol, it's no use trying other providers if connection on that protocol failed. Or when engine reported some internal database error (except invalid ODS version) it's no use trying to open that database with loopback provider.

It seems that it's better to enumerate error codes after which trying other providers makes sense - that's first of all isc_unavailable and isc_no_priv, but due to historical reasons (content of status vector for known conditions should be kept as it was) adding some more error codes is needed.

Commits: b658497 FirebirdSQL/fbt-repository@f780e5d