chore(validation): move functions from constants

- Move validation functions from `internal/constants` to `internal/configuration/settings/validation`
- Concatenate all OpenVPN constants in `internal/constants/openvpn.go`

internal/updater/providers/surfshark/remaining.go

@@ -6,7 +6,8 @@ import (
 
 // getRemainingServers finds extra servers not found in the API or in the ZIP file.
 func getRemainingServers(hts hostToServer) {
-	hostnameToLocationLeft := constants.SurfsharkHostToLocation()
+	locationData := constants.SurfsharkLocationData()
+	hostnameToLocationLeft := hostToLocation(locationData)
 	for _, hostnameDone := range hts.toHostsSlice() {
 		delete(hostnameToLocationLeft, hostnameDone)
 	}