Handle validation of nested query parameters e.g. ?filter[groupId]=

[HughbertD]

Nested query parameters such as ?filter[groupId] always return null during the validation.

This is due to $this->request->query->has being a pretty simple Symfony implementation (as documented https://github.com/laravel/framework/issues/33376)

This adds some support to getting these nested query parameters in the recommended way from the query string.

Fixes #130

[ethanbray]

@hotmeteor I appreciate you're probably busy but is there any chance we can get this reviewed/merged? We make heavy usage of nested query parameters and this is posing an issue for us.

[hotmeteor]

Done