[Doctrine] added QueryBuilderHelper for adding the WhereCase to a QueryBuilder object

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #23 
| License       | MIT

This adds the QueryBuilderHelper for adding the WhereCase to a QueryBuilder object.
There were some issues with making the WhereBuilder compatible with the ORM QueryBuilder, the QueryBuilder has no hints so these need to be passed manually. And I did not feel comfortable with adding two getters for this edge case.

The WhereBuilder is already very coupled so adding two other methods would not contribute to a more clean code base.