feat(openamt): Configuration of the OpenAMT capability [INT-6] (#6071)

Co-authored-by: Sven Dowideit <sven.dowideit@portainer.io>

api/hostmanagement/openamt/authorization.go

@@ -0,0 +1,52 @@
+package openamt
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+
+	portainer "github.com/portainer/portainer/api"
+)
+
+type authenticationResponse struct {
+	Token string `json:"token"`
+}
+
+func (service *Service) executeAuthenticationRequest(configuration portainer.OpenAMTConfiguration) (*authenticationResponse, error) {
+	loginURL := fmt.Sprintf("https://%s/mps/login/api/v1/authorize", configuration.MPSURL)
+
+	payload := map[string]string{
+		"username": configuration.Credentials.MPSUser,
+		"password": configuration.Credentials.MPSPassword,
+	}
+	jsonValue, _ := json.Marshal(payload)
+
+	req, err := http.NewRequest(http.MethodPost, loginURL, bytes.NewBuffer(jsonValue))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	response, err := service.httpsClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	responseBody, readErr := ioutil.ReadAll(response.Body)
+	if readErr != nil {
+		return nil, readErr
+	}
+	errorResponse := parseError(responseBody)
+	if errorResponse != nil {
+		return nil, errorResponse
+	}
+
+	var token authenticationResponse
+	err = json.Unmarshal(responseBody, &token)
+	if err != nil {
+		return nil, err
+	}
+
+	return &token, nil
+}