fix(protonvpn): authenticated servers data updating (#2878)

- `-proton-username` flag for cli update
- `-proton-password` flag for cli update
- `UPDATER_PROTONVPN_USERNAME` option for periodic updates
- `UPDATER_PROTONVPN_PASSWORD` option for periodic updates

internal/provider/protonvpn/provider.go

@@ -18,11 +18,12 @@ type Provider struct {
 
 func New(storage common.Storage, randSource rand.Source,
 	client *http.Client, updaterWarner common.Warner,
+	username, password string,
 ) *Provider {
 	return &Provider{
 		storage:    storage,
 		randSource: randSource,
-		Fetcher:    updater.New(client, updaterWarner),
+		Fetcher:    updater.New(client, updaterWarner, username, password),
 	}
 }