ACS doesn't let me create isolated networks with ranges which are not RFC1918

##### ISSUE TYPE

* Bug Report

##### COMPONENT NAME

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API, UI, logic
~~~

##### CLOUDSTACK VERSION

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4.18
~~~

##### CONFIGURATION

N/A

##### OS / ENVIRONMENT

KVM with Tungsten Fabric

##### SUMMARY

I want to create an isolated network with Public IPs which will be then routed with a Tungsten Logical Router.

##### STEPS TO REPRODUCE

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-> Add Network, Isolated. In Gateway place a non-RFC1918 range.
~~~

##### EXPECTED RESULTS

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For the network to be created with that range
~~~

##### ACTUAL RESULTS

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"Virtual Guest Cidr 33.65.45.0/24 is not RFC 1918 or 6598 compliant"
~~~

Reproduce el flujo Add Network → Isolated en CloudStack 4.18 con KVM y Tungsten Fabric, utilizando un rango de gateway que no sea RFC1918. Empieza siguiendo la validación de la API, la UI y la lógica que produce el error RFC 1918 o 6598. Se considera completado cuando se puede crear una red aislada con el rango público solicitado, manteniendo la validación adecuada para los rangos no compatibles.

Escrito por el modelo de indexación a partir del texto del issue.