Dynamic UI components (#1162)

Hide/Show UI components based on the IAM policy of the current user

- Buckets lists: hide/show manage button
- Bucket admin page: left menu items enable/disable
- Bucket admin page: bucket configuration buttons are enabled/disabled
- Bucket admin page: hide/show create buttons
- Bucket admin page: enable/disable requests to backend service
- Object browser: hide/show bucket buttons for upload, delete, etc
- Object browser: hide/show bucket configuration button
- Object details: hide/show object buttons, ie: delete
- Object details: hide/show object attributes, ie: legal hold,
  retention, tags, etc

Signed-off-by: Lenin Alevski <alevsk.8772@gmail.com>

Co-authored-by: Daniel Valdivia <18384552+dvaldivia@users.noreply.github.com>

restapi/user_session.go

@@ -18,6 +18,7 @@ package restapi
 
 import (
 	"context"
+	"encoding/json"
 	"net/http"
 	"net/url"
 	"time"
@@ -84,6 +85,17 @@ func getSessionResponse(session *models.Principal) (*models.SessionResponse, *mo
 		return nil, prepareError(err, errorGenericInvalidSession)
 	}
 	userAdminClient := AdminClient{Client: mAdminClient}
+	// Policy used by the current user
+	accountInfo, err := userAdminClient.AccountInfo(ctx)
+	if err != nil {
+		return nil, prepareError(err)
+	}
+
+	var sessionPolicy *models.IamPolicy
+	err = json.Unmarshal(accountInfo.Policy, &sessionPolicy)
+	if err != nil {
+		return nil, prepareError(err)
+	}
 	// Obtain the current policy assigned to this user
 	// necessary for generating the list of allowed endpoints
 	policy, err := getAccountPolicy(ctx, userAdminClient)
@@ -105,6 +117,7 @@ func getSessionResponse(session *models.Principal) (*models.SessionResponse, *mo
 		Status:          models.SessionResponseStatusOk,
 		Operator:        false,
 		DistributedMode: isErasureMode(),
+		Policy:          sessionPolicy,
 	}
 	return sessionResp, nil
 }