Fix 2379 - Mirror and region definitions

[svartkanin]

This fixes #2379
To fix the reported problem and addressing the comment from @Torxed #2379 (comment) the mirror and region configuration has been reworked.
The major changes

• There are new configuration options for mirror servers and repositories and the menu entries have been renamed to make it clearer
  • Select regions -> Select the mirror regions (Same as currently)
  • Add custom servers -> NEW allows to define custom mirror servers
  • Add custom repositories -> Has been renamed to avoid confusion
• The Additional repositories menu entry has been moved from the global menu into the Mirrors and repositories submenu to keep them all together and also renamed to Optional repositories
• The mirror_config entry has been adjusted in the user_configuration.json to reflect the configuration changes but it is backwards compatible so that existing configurations will not break

  "mirror_config": {
    "custom_servers": [
        {
          "url": "https://mymirror.com/$repo/os/$arch"
        }
    ],
    "mirror_regions": {
      "Australia": [
        "http://archlinux.mirror.digitalpacific.com.au/$repo/os/$arch"
      ]
    },
    "optional_repositories": [
      "testing"
    ],
    "custom_repositories": [
      {
        "name": "myrepo",
        "url": "https://myrepo.com/$repo/os/$arch",
        "sign_check": "Required",
        "sign_option": "TrustAll"
      }
    ]
  },

The custom_servers and mirror_regions configurations will only modify the /etc/pacman.d/mirrorlist configuration file, whereas the optional_repositories and custom_repositories will modify the /etc/pacman.conf accordingly.

[Torxed]

Looks good, and once we have libalpm implemented we can (in the future) make sure that archinstall works against a local instance of pacman to not conflict/modify the distro settings.

Since archinstall is intended to be used in a live ISO, it's not a huge issue. But it will be cleaner in the future to make sure we use our own instance/config for pacman.

But this is a welcome PR!

[svartkanin]

Yes that'd be great, during testing my config obviously got modified all the time which wasn't the best hehe

[neitsab]

Thanks, this is a great addition! 🙏🏻