Add duplicateKeys property to Insert, BatchInsert, and MultiInsert annotations

[nakamura-to]

This pull request allows specifying the keys to be used for duplicate checks:

@Dao
public interface EmployeeDao {

  @Insert(duplicateKeyType = DuplicateKeyType.UPDATE, duplicateKeys = {"employeeNo"})
  int insert(Employee employee);

  @BatchInsert(duplicateKeyType = DuplicateKeyType.UPDATE, duplicateKeys = {"employeeNo"})
  int[] insertBatch(List<Employee> employees);

  @MultiInsert(duplicateKeyType = DuplicateKeyType.UPDATE, duplicateKeys = {"employeeNo"})
  int insertMulti(List<Employee> employees);
}

When using PostgreSQL, the following SQL will be generated:

insert into EMPLOYEE as target (EMPLYEE_ID, EMPLYEE_NO, EMPLYEE_NAME, VERSION) values (?, ?, ?, ?) on conflict (EMPLYEE_NO) do update set EMPLYEE_NAME = excluded.EMPLYEE_NAME, VERSION = excluded.VERSION

The specified keys are used in the ON CONFLICT clause.

For DBMSs like MySQL, where specifying a key isn't supported, the duplicateKeys property will be disregarded.

[nakamura-to]

@momosetkn @orekyuu We thought this feature might catch your interest. If you have any questions or concerns, feel free to leave a comment.