Implement Nexus Collection (#3)

* Implement Nexus Collection

* Add `ClosureIteratorAggregate`

* Add `CollectionInterface::wrap()`

* Add `Collection`

* Add tests

* Add `all` operation

* Add `values` operation

* Add `keys` operation

* Add `CollectionTypeInferenceTest`

* Add `filter` operation

* Add `filterKeys` operation

* Add `filterWithKey` operation

* Add test for sorting of collection methods

* Add mutation testing for collections

* Add `map` operation

* Add `mapKeys` operation

* Fix type inferences in phpstan 2.0

* Add example code for MapKeys

* Add `mapWithKey` operation

* Add `slice` operation

* Add `iterator_to_array` false negative to baseline

* Add `drop` operation

* Add `take` operation

* Add `tap` operation

* Remove redundant PHPDocs

* Fix templates for `Collection::wrap()`

* Add `chunk` operation

* Add `limit` operation

* Add `cycle` operation

* Add `RewindableIterator`

* Add `diff` operation

* Add `diffKey` operation

* Add `flip` operation

* Add `reject` operation

* Remove code examples in PHPDocs

* Add `partition` operation

* Refactor `toArrayKey` and `generateDiffHashTable` to separate methods

* Add `intersect` operation

* Add `intersectKey` operation

* Add `associate` operation

* Add `reductions` operation

* Add `append` operation

* Add `get` operation

* Add `has` operation

* Add `first` operation

* Add `forget` operation

* Add `reduce` operation

* Add `any` operation

* Add `every` operation

* Reformat code