Update Hostgroup client and add stratos validation (IBM-Cloud#361)

* Update Hostgroup client and add stratos validation

* Update name to hostGroup pattern

* Rename file

examples/hostgroups/main.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+	"log"
+
+	v "github.com/IBM-Cloud/power-go-client/clients/instance"
+	ps "github.com/IBM-Cloud/power-go-client/ibmpisession"
+	"github.com/IBM/go-sdk-core/v5/core"
+)
+
+func main() {
+	//session Inputs
+	//  < IAM TOKEN >
+	// token := ""
+	apiKey := ""
+	region := " < REGION > "
+	zone := " < ZONE > "
+	accountID := " < ACCOUNT ID > "
+	url := region + ".power-iaas.test.cloud.ibm.com"
+
+	// dr location inputs
+	piID := " < POWER INSTANCE ID > "
+
+	// authenticator := &core.BearerTokenAuthenticator{
+	// 	BearerToken: token,
+	// }
+	authenticator := &core.IamAuthenticator{
+		ApiKey: apiKey,
+		// Uncomment for test environment
+		URL: "https://iam.test.cloud.ibm.com",
+	}
+
+	// Create the session
+	options := &ps.IBMPIOptions{
+		Authenticator: authenticator,
+		UserAccount:   accountID,
+		Zone:          zone,
+		URL:           url,
+		Debug:         true,
+	}
+	session, err := ps.NewIBMPISession(options)
+	if err != nil {
+		log.Fatal(err)
+	}
+	powerClient := v.NewIBMPHostgroupsClient(context.Background(), session, piID)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	getAllAvailableHost, err := powerClient.GetAvailableHosts()
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Printf("***************[0]****************** %+v \n", getAllAvailableHost)
+
+	getHostgroups, err := powerClient.GetHostGroups()
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Printf("***************[1]****************** %+v \n", getHostgroups)
+}