NEW PROVIDER: CSCGLOBAL as DNS Service Provider (#1516)

* Move the registrar features to a separate file

* Prepare the testing framework

* Roughed out functions

* Fix up structs

* WIP!

* First tests pass

* wip!

* Flesh out remaining rTypes, get nameservers, etc

* Fix TXT records

* Clean up code

* More cleanups. Fix CAA/SRV

* Linting

* Cleanups/linting

* Fix CAA [more] and more cleanups

* CSC does not like very long txt records

* Use timer only when interactive

* Disable CAA for now

* Update docs

* Remove debug printf

* add go-isatty

* cleanups

providers/cscglobal/registrar.go

@@ -0,0 +1,42 @@
+package cscglobal
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/StackExchange/dnscontrol/v3/models"
+)
+
+// GetRegistrarCorrections gathers corrections that would being n to match dc.
+func (client *providerClient) GetRegistrarCorrections(dc *models.DomainConfig) ([]*models.Correction, error) {
+	nss, err := client.getNameservers(dc.Name)
+	if err != nil {
+		return nil, err
+	}
+	foundNameservers := strings.Join(nss, ",")
+
+	expected := []string{}
+	for _, ns := range dc.Nameservers {
+		if ns.Name[len(ns.Name)-1] == '.' {
+			// When this code was written ns.Name never included a single trailing dot.
+			// If that changes, the code should change too.
+			return nil, fmt.Errorf("name server includes a trailing dot, has the API changed?")
+		}
+		expected = append(expected, ns.Name)
+	}
+	sort.Strings(expected)
+	expectedNameservers := strings.Join(expected, ",")
+
+	if foundNameservers != expectedNameservers {
+		return []*models.Correction{
+			{
+				Msg: fmt.Sprintf("Update nameservers %s -> %s", foundNameservers, expectedNameservers),
+				F: func() error {
+					return client.updateNameservers(expected, dc.Name)
+				},
+			},
+		}, nil
+	}
+	return nil, nil
+}