Feature: add more Surfshark servers

- Add servers missing from surfshark zip file
- Fixes #424 and re-add multihop servers
- Fix logic to try resolving old vpn servers for Surfshark

internal/constants/servers_test.go

@@ -183,7 +183,7 @@ func Test_timestamps(t *testing.T) {
 		"Surfshark": {
 			servers:   allServers.Surfshark.Servers,
 			timestamp: allServers.Surfshark.Timestamp,
-			digest:    "1a7f38bb",
+			digest:    "c090bcd9",
 		},
 		"Torguard": {
 			servers:   allServers.Torguard.Servers,