Wireguard Peer Generator - Improvements for better user experience

[stavros-k]

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Is your feature request related to a problem? Please describe.

A clear and concise description of what the problem is including your motivation for the request,
i.e. "For the purpose of [...] I am missing a solution that will [...]."

Bellow I'm summing some ideas I have. Browsing other issues to see if mine was duplicates. I found couple others scattered, and I thought it would be nice to sum them up here.

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Describe the solution you like

• Validate the Endpoint that it has a port (otherwise wireguard app says invalid QR) 3f6b9ec
• Allow the usage of alias (networks) in the Allowed IPs field
• Allowed IPs should be "chip" (see image) entries and then joined by comma on the config
  
• Besides the QR, it would be nice to have a Download config button (WireGuard Peer generator - Config download button #7360)
• Allowed IPs should be "saved" when clicking Store and generate next (Wireguard Peer Generator - Allowed IPs is correctly added to the peer config however it should not be added to the server side config when saved #7359 (comment))
• Keepalive should be "saved" when clicking Store and generate next

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Describe alternatives you considered

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Additional context

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