Azure-DNS: store values in TXT records without additional quotes

```improvement operator
Azure-DNS: store values in TXT records without additional quotes
```

pkg/controller/provider/azure/execution.go

@@ -17,6 +17,7 @@
 package azure
 
 import (
+	"strconv"
 	"strings"
 
 	azure "github.com/Azure/azure-sdk-for-go/services/dns/mgmt/2018-03-01-preview/dns"
@@ -106,7 +107,12 @@ func (exec *Execution) buildMappedRecordSet(name string, rset *dns.RecordSet) (b
 		recordType = azure.TXT
 		txtrecords := []azure.TxtRecord{}
 		for _, r := range rset.Records {
-			txtrecords = append(txtrecords, azure.TxtRecord{Value: &[]string{r.Value}})
+			// AzureDNS stores value as given, i.e. including quotes, so text value must be unquoted
+			unquoted, err := strconv.Unquote(r.Value)
+			if err != nil {
+				unquoted = r.Value
+			}
+			txtrecords = append(txtrecords, azure.TxtRecord{Value: &[]string{unquoted}})
 		}
 		properties.TxtRecords = &txtrecords
 	default:

pkg/controller/provider/azure/handler.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"fmt"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"github.com/gardener/controller-manager-library/pkg/logger"
@@ -193,7 +194,12 @@ func (h *Handler) GetZoneState(zone provider.DNSHostedZone) (provider.DNSZoneSta
 		if item.TxtRecords != nil {
 			rs := dns.NewRecordSet(dns.RS_TXT, *item.TTL, nil)
 			for _, record := range *item.TxtRecords {
-				rs.Add(&dns.Record{Value: strings.Join(*record.Value, "\n")})
+				quoted := strings.Join(*record.Value, "\n")
+				// AzureDNS stores values unquoted, but it is expected to be quoted in dns.Record
+				if len(quoted) > 0 && quoted[0] != '"' && quoted[len(quoted)-1] != '"' {
+					quoted = strconv.Quote(quoted)
+				}
+				rs.Add(&dns.Record{Value: quoted})
 			}
 			dnssets.AddRecordSetFromProvider(fullName, rs)
 		}