Cyberghost support (#168)

* Host finder CLI for cyberghost
* Resolver program updated with Cyberghost data
* Gluetun cli clientkey subcommand

internal/params/cyberghost.go

@@ -0,0 +1,29 @@
+package params
+
+import (
+	"strings"
+
+	libparams "github.com/qdm12/golibs/params"
+	"github.com/qdm12/private-internet-access-docker/internal/constants"
+	"github.com/qdm12/private-internet-access-docker/internal/models"
+)
+
+// GetCyberghostGroup obtains the server group for the Cyberghost server from the
+// environment variable CYBERGHOST_GROUP
+func (p *reader) GetCyberghostGroup() (region models.CyberghostGroup, err error) {
+	s, err := p.envParams.GetValueIfInside("CYBERGHOST_GROUP", constants.CyberghostGroupChoices())
+	return models.CyberghostGroup(strings.ToLower(s)), err
+}
+
+// GetCyberghostRegion obtains the country name for the Cyberghost server from the
+// environment variable REGION
+func (p *reader) GetCyberghostRegion() (region models.CyberghostRegion, err error) {
+	s, err := p.envParams.GetValueIfInside("REGION", constants.CyberghostRegionChoices())
+	return models.CyberghostRegion(strings.ToLower(s)), err
+}
+
+// GetCyberghostClientKey obtains the one line client key to use for openvpn from the
+// environment variable CLIENT_KEY
+func (p *reader) GetCyberghostClientKey() (clientKey string, err error) {
+	return p.envParams.GetEnv("CLIENT_KEY", libparams.Compulsory(), libparams.CaseSensitiveValue())
+}