Allow for the extension of the JdbcQueryLookupStrategy

[mipo256]

We're writing our own dialect for the Spring Data JDBC aiming to support YDB. And we hit the problem: ydb-platform/ydb-java-dialects#173

The summary is that we seems to need to extend the QueryLookupStrategy. That is not a big deal, since it is public, however, we want to retian the logic of the RowMapper selection mechanism, as well as resolution of the StringBased/PartTree queries. This logic is outlined in the JdbcQueryLookupStrategy, which is apparently not public.

Proposal: Since the QueryLookupStrategy is constructed in JdbcRepositoryFactory, therefore it actually is intended to be overloaded, can we make the JdbcQueryLookupStrategy and its subclasses in JDBC module public as well?

I have the PR ready for this, waiting for the approval. CC: @schauder @mp911de

[schauder]

I wonder if we could extract the RowMapper selection mechanism into a top level public class. Would that work for you?

[mipo256]

That is great, but that is not enough.

We really need the logic encapsulated in the DeclaredQueryLookupStrategy and CreateQueryLookupStrategy. If we made them public as well, that would be great and that would work. May I provide the PR? I have the code ready.

[schauder]

Sure, there is no harm in having a PR