MC-3735: Allow inline WYSIWYG editing of slides

- fix text selection in wysiwyg

Author: omiroshnichenko

app/code/Magento/PageBuilder/view/adminhtml/web/template/content-type/slide/collage-centered/preview.html

@@ -22,6 +22,7 @@
                  attr="data.content.attributes"
                  ko-style="data.content.style"
                  css="data.content.css"
+                 event="mousedown: stopEvent"
                  afterRender="initWysiwyg">
                 <div html="data.content.html"></div>
             </div>

app/code/Magento/PageBuilder/view/adminhtml/web/template/content-type/slide/collage-left/preview.html

@@ -24,6 +24,7 @@
                  attr="data.content.attributes"
                  ko-style="data.content.style"
                  css="data.content.css"
+                 event="mousedown: stopEvent"
                  afterRender="initWysiwyg">
                 <div html="data.content.html"></div>
             </div>

app/code/Magento/PageBuilder/view/adminhtml/web/template/content-type/slide/collage-right/preview.html

@@ -22,6 +22,7 @@
                  attr="data.content.attributes"
                  ko-style="data.content.style"
                  css="data.content.css"
+                 event="mousedown: stopEvent"
                  afterRender="initWysiwyg">
                 <div html="data.content.html"></div>
             </div>

app/code/Magento/PageBuilder/view/adminhtml/web/template/content-type/slide/poster/preview.html

@@ -26,6 +26,7 @@
                      attr="data.content.attributes"
                      ko-style="data.content.style"
                      css="data.content.css"
+                     event="mousedown: stopEvent"
                      afterRender="initWysiwyg">
                     <div html="data.content.html"></div>
                 </div>