Add support for multiple aspect ratios

[Mth0158]

Like content_type, we should be able to support multiple aspect ratios.

Possible to get inspiration from this fork: master...nejdetkadir:active_storage_validations:master. But not too much because they modified the :with option, we would rather like something with :in like content_type validator does.

Do not forget to add tests to your validator update + update the associated matcher

Please notify the fork owner so he/she can update its gemfile