Request to improve updateNetwork api

##### ISSUE TYPE

* Improvement Request / Future request

##### COMPONENT NAME

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API
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##### CLOUDSTACK VERSION

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4.18.1.0
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##### CONFIGURATION

N/A
##### OS / ENVIRONMENT

N/A

##### SUMMARY

Request to improve updateNetwork api to add/change ipv6 CIRD, ipv6 gate, ipv6 end ,start ip, router ipv6.

##### STEPS TO REPRODUCE

Create ipv4 only guest network. Try to add ipv6 CIDR, gateway, start ip, end ip.

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##### EXPECTED RESULTS

Possibility to change the settings described above using the interface or api
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##### ACTUAL RESULTS

You won't be able to do this either through the interface or the api

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从 updateNetwork API 入口点开始，针对 IPv4-only 客户机网络重现该请求。确定通过 API 和界面更改 IPv6 CIDR、网关、起始和结束 IP 以及路由器 IPv6 时的预期行为。当能够通过所请求的路径成功更改这些设置时，即视为完成。

由索引模型根据 Issue 内容生成。