setCaption of Panel did not honor setCaptionAsHtml (#11523)

Verify that correct mode(HTML/TEXT) of caption is set for the  Panel
Fixes #11521

client/src/main/java/com/vaadin/client/ui/VPanel.java

     }
 
     /** For internal use only. May be removed or replaced in the future. */
-    public void setCaption(String text) {
-        DOM.setInnerHTML(captionText, text);
+    public void setCaption(String text, boolean captionAsHtml) {
+        if (captionAsHtml) {
+            captionText.setInnerHTML(text);
+        } else {
+            captionText.setInnerText(text);
+        }
     }
 
     /** For internal use only. May be removed or replaced in the future. */

client/src/main/java/com/vaadin/client/ui/panel/PanelConnector.java

             panel.captionNode.setClassName(VPanel.CLASSNAME + "-caption");
             boolean hasCaption = hasCaption();
             if (hasCaption) {
-                panel.setCaption(getState().caption);
+                panel.setCaption(getState().caption,getState().captionAsHtml);
             } else {
-                panel.setCaption("");
+                panel.setCaption("",false);
                 panel.captionNode.setClassName(VPanel.CLASSNAME + "-nocaption");
             }
 

uitest/src/main/java/com/vaadin/tests/components/panel/PanelChangeContents.java

         buttons.addComponent(companiesButton);
         buttons.addComponent(settingsButton);
         panel = new Panel();
+        panel.setCaption("<div class=\"caption-with-html\">Caption</div>");
         panel.setSizeFull();
         panel.setContent(stats);
         content.addComponent(buttons);

uitest/src/main/java/com/vaadin/tests/components/panel/PanelHTMLCaption.java

+package com.vaadin.tests.components.panel;
+
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.ui.Panel;
+import com.vaadin.ui.Button;
+import com.vaadin.ui.VerticalLayout;
+
+public class PanelHTMLCaption extends AbstractTestUI {
+    public static final String caption = "<b> <div id='divId'>BOLD CAPTION</div></b>";
+
+    @Override
+    protected void setup(VaadinRequest request) {
+        Panel panel = new Panel();
+        panel.setId("panelId");
+        panel.setWidth("200px");
+        panel.setHeight("200px");
+
+        panel.setCaption(caption);
+        panel.setCaptionAsHtml(false);
+
+        panel.setContent(new VerticalLayout());
+
+        addComponent(panel);
+        Button changeCaptionFormat = new Button("Set Caption as HTML", e -> {
+            panel.setCaptionAsHtml(true);
+        });
+        changeCaptionFormat.setId("buttonId");
+        addComponent(changeCaptionFormat);
+    }
+}

uitest/src/test/java/com/vaadin/tests/components/panel/PanelChangeContentsTest.java

 
 import org.junit.Test;
 
+import com.vaadin.testbench.By;
 import com.vaadin.tests.tb3.MultiBrowserTest;
 
 public class PanelChangeContentsTest extends MultiBrowserTest {
                 "/VVerticalLayout[0]/Slot[1]/VPanel[0]/VVerticalLayout[0]/Slot[0]/VLabel[0]")
                         .getText());
 
+        assertElementNotPresent(By.className("caption-with-html"));
     }
 }

uitest/src/test/java/com/vaadin/tests/components/panel/PanelHTMLCaptionTest.java

+package com.vaadin.tests.components.panel;
+
+import com.vaadin.tests.tb3.MultiBrowserTest;
+import org.junit.Test;
+import org.openqa.selenium.By;
+
+
+public class PanelHTMLCaptionTest extends MultiBrowserTest {
+    @Test
+    public void testCaptionDisplayedAsText() {
+        openTestURL();
+        assertElementNotPresent(By.id("divId"));
+        findElement(By.id("buttonId")).click();
+        assertElementPresent(By.id("divId"));
+    }
+}