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"
~~~

在 CloudStack 4.18 上使用 KVM 和 Tungsten Fabric，通过非 RFC1918 网关范围重现 Add Network → Isolated 流程。首先跟踪生成 RFC 1918 或 6598 错误的 API、UI 和逻辑验证。完成的标准是能够使用请求的公共范围创建隔离网络，同时保留对不支持范围的适当验证。

由索引模型根据 Issue 内容生成。