cli: add fallback query support for debug zip

Previously, when SQL queries for dumping tables to debug zip would
fail, we would have no follow-up. Engineers can now define "fallback"
queries for tables in debug zip in order to make a second attempt
with a simpler query. Often we want to run a more complex query to
gather more debug data but these queries can fail when the cluster
is experiencing problems. This change gives us a chance to define a
simpler approach that can be attempted when necessary.

In order to define a fallback, there are two new optional fields in
the `TableRegistryConfig` struct for redacted and unredacted queries
respectively.

Debug zip output will still include the failed attempts at the
original query along with the error message file as before. If a
fallback query is defined, that query will produce its own output (and
error) file with an additional `.fallback` suffix added to the base
table name to identify it.

Resolves: cockroachdb#123964
Epic: CRDB-35278

Release note: None