Maintenance: refactor servers updater code

- Require at least 80% of number of servers now to pass
- Each provider is in its own package with a common structure
- Unzip package with unzipper interface
- Openvpn package with extraction and download functions

internal/updater/providers/protonvpn/sort.go

@@ -0,0 +1,26 @@
+package protonvpn
+
+import (
+	"sort"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func sortServers(servers []models.ProtonvpnServer) {
+	sort.Slice(servers, func(i, j int) bool {
+		a, b := servers[i], servers[j]
+		if a.Country == b.Country { //nolint:nestif
+			if a.Region == b.Region {
+				if a.City == b.City {
+					if a.Name == b.Name {
+						return a.Hostname < b.Hostname
+					}
+					return a.Name < b.Name
+				}
+				return a.City < b.City
+			}
+			return a.Region < b.Region
+		}
+		return a.Country < b.Country
+	})
+}