Add possibility to set max and min memory (dynamic memory) in Hyper-V builder

_This issue was originally opened by @meteor1997 as hashicorp/packer#9827. It was migrated here as a result of the [Packer plugin split](https://github.com/hashicorp/packer/issues/8610#issuecomment-770034737). The original body of the issue is below._

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#### Description

Right now the Hyper-V builder will take some standard values for the max and min memory when using the enable_dynamic_memory feature.

It would be nice to have the possibility to configure the max and min memory of the vm.