Improve the UI/API related to site to site vpn connections

### The required feature described as a wish

As admin user currently to identify the relation between vpc, vpn connections , site to site vpn , vpn customer gateway, vpngateways is difficult from api and also from the ui prespective

It would be great we could improve the api and Ui related operations to site to site vpn

https://docs.cloudstack.apache.org/en/4.22.1.0/adminguide/networking/site_to_site_vpn.html

UI/API Issue 1: Show the associated s2svpngatewayid and s2scustomergatewayid and vpc in the vpn connections page

Navigate to Network > VPN Connections

The listVpnConnections has the s2scustomergatewayid and s2svpngatewayid in the api response and also vpcid as a parameter

https://cloudstack.apache.org/api/apidocs-4.22/apis/listVpnConnections.html

Expected behaviour

As Admin user i would like to know to which to vpn customer gateway ( name) and to which vpc (name) that a particular vpn connection is assoicated with.

Remembering the IP address and UUID is not possible

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UI/API Issue 2: Differnt views present when creating a vpn connection

Navigate > Network > Create VPN connection >

Navigate > Network > VPC > VPN Connection > Create Site to Site VPN Connection

Expected behaviour

Show a consistent form to avoid confusion

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UI issue 3: Rename ( Network > Site-to-Site VPN ) to VPN gateways

Its calling the listVpnGateways api

https://cloudstack.apache.org/api/apidocs-4.22/apis/listVpnGateways.html

Expected behaviour

The site to site vpn is not a proper name

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UI issue 4: Show the VPC details in the main page Network > Site to Site VPN

The vpc details is visible after clicking the IP address

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UI/Api issue 5: Show the VPC associated with VPN customer gateways

https://cloudstack.apache.org/api/apidocs-4.22/apis/listVpnCustomerGateways.html

Network > VPN Customer gateway

首先，结合 listVpnConnections、listVpnGateways 和 listVpnCustomerGateways API 文档，检查 Network > VPN Connections、Site-to-Site VPN、VPN gateways 和 VPN Customer gateway 视图。比较两种 VPN 连接创建流程，并确定现有响应如何公开 VPC 和网关关联。完成标准是：相关名称和 VPC 详细信息在列出的视图中可见，并且创建表单保持一致。

由索引模型根据 Issue 内容生成。