[FEATURE]: ignore undefined values in `AND` array in the query builder

### Feature hasn't been suggested before.

- [x] I have verified this feature I'm about to request hasn't been suggested before.

### Describe the enhancement you want to request

It would be nice to be able to specify some optional conditions in the query builder when using `AND: [...]` by returning undefined for some array elements, when a particular condition is not needed (at runtime). Right now, it throws a type error, because `AND` doesn't support undefined values. It should just ignore those and filter them out, like the `and()` function does.

Start by locating the query-builder implementation for AND arrays and the existing and() handling referenced in the issue. Check how undefined values are typed and processed, then find the related query-builder tests. Done means optional AND conditions can be returned as undefined without a type error and are ignored at runtime, while existing conditions retain their behavior.

Written by the indexing model from the issue text.