Convenient way to create custom query

[lavrukov]

Nowadays, creating custom queries in YOJ is very difficult, which restrict users and forces them to dodge. We need to provide a convenient way.

What's difficult now:

• Need to inherit from YdbRepositoryTransaction to gain access to execute
• Need to inherit from InMemoryRepositoryTransaction to implement logic over inMemory
• You cannot conveniently write the code in one place and then simply call it.

What we want:

• Have a main YOJ-way to implement custom query in one file for YDB and InMemory (can split if desired)
• Don't need to register query or touch any code around

Proposal:

• public interface CustomQuery<PARAMS, RESULT> {}
• Extend the Tx interface by adding the method <PARAMS, RESULT> RESULT customQuery(CustomQuery<PARAMS, RESULT> query, PARAMS params)
• YDB interface

  public interface YdbCustomQuery<PARAMS, RESULT> extends CustomQuery<PARAMS, RESULT> {
   Statement<PARAMS, RESULT> executeOnYdb(PARAMS params);
  }

• InMemory interface

  public interface InMemoryCustomQuery<PARAMS, RESULT> extends CustomQuery<PARAMS, RESULT> {
    RESULT executeOnInMemory(PARAMS params, {public interfaces to InMemoryStorage});
  }

• In this case, the implementation of the custom request will be in one file

  public class MySelect implements YdbCustomQuery<List<MyEntity.Id>, List<MyEntity>>, InMemoryCustomQuery<List<MyEntity.Id>, List<MyEntity>> {
   // ...
  }

• Usage:

  List<MyEntity> entities = tx.customQuery(MySelect.INSTANCE, List.of(e1.id(), e2.id(), e3.id()))

• If you don't use InMemory you can implement only YdbCustomQuery

[lavrukov]

With this we should think about how to pass parametrs to query without batabind-magic. For example, we can do something like this QueryParametr.builder(MyEntity.class).field("myFieldTimestamp").value(Instant.now()) and use it to convert value to ydb view with all databind rules

Updated: looks like we need think about using classes from https://github.com/ydb-platform/yoj-project/issues/52 for this case