updater: refactoring and set DNS server correctly

- Fix CLI operation not setting DNS server
- Fix periodic operation not setting DNS server
- Set DNS address for resolution once at start for both CLI and periodic operation
- Inject resolver to each provider instead of creating it within
- Use resolver settings on every call to `.Resolve` method, instead of passing it to constructor
- Move out minServers check from resolver

internal/cli/openvpnconfig.go

@@ -3,6 +3,7 @@ package cli
 import (
 	"context"
 	"fmt"
+	"net"
 	"net/http"
 	"strings"
 	"time"
@@ -11,6 +12,7 @@ import (
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/provider"
 	"github.com/qdm12/gluetun/internal/storage"
+	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
 type OpenvpnConfigLogger interface {
@@ -23,6 +25,11 @@ type Unzipper interface {
 		contents map[string][]byte, err error)
 }
 
+type ParallelResolver interface {
+	Resolve(ctx context.Context, settings resolver.ParallelSettings) (
+		hostToIPs map[string][]net.IP, warnings []string, err error)
+}
+
 func (c *CLI) OpenvpnConfig(logger OpenvpnConfigLogger, source sources.Source) error {
 	storage, err := storage.New(logger, constants.ServersData)
 	if err != nil {
@@ -42,8 +49,9 @@ func (c *CLI) OpenvpnConfig(logger OpenvpnConfigLogger, source sources.Source) e
 	unzipper := (Unzipper)(nil)
 	client := (*http.Client)(nil)
 	warner := (Warner)(nil)
+	parallelResolver := (ParallelResolver)(nil)
 
-	providers := provider.NewProviders(storage, time.Now, warner, client, unzipper)
+	providers := provider.NewProviders(storage, time.Now, warner, client, unzipper, parallelResolver)
 	providerConf := providers.Get(*allSettings.VPN.Provider.Name)
 	connection, err := providerConf.GetConnection(allSettings.VPN.Provider.ServerSelection)
 	if err != nil {