fix(Utils): use the more robust QClipboardProxy checks

- when verifying whether an image has a suitable size or extension

ui/imports/utils/Utils.qml

@@ -3,6 +3,8 @@ pragma Singleton
 import QtQuick 2.13
 
 import shared 1.0
+
+import StatusQ 0.1
 import StatusQ.Core.Theme 0.1
 import StatusQ.Core.Utils 0.1 as StatusQUtils
 
@@ -335,16 +337,15 @@ QtObject {
     }
 
     function isValidDragNDropImage(url) {
-        let lowerCaseUrl = url.toLowerCase()
-        return Constants.acceptedDragNDropImageExtensions.some(ext => lowerCaseUrl.endsWith(ext)) ||
-            lowerCaseUrl.startsWith(Constants.dataImagePrefix);
+        return url.startsWith(Constants.dataImagePrefix) ||
+                QClipboardProxy.isValidImageUrl(url, Constants.acceptedDragNDropImageExtensions)
     }
 
     function isFilesizeValid(img) {
         if (img.startsWith(Constants.dataImagePrefix)) {
             return img.length < maxImgSizeBytes
         }
-        let size = parseInt(globalUtils.getFileSize(img))
+        const size = QClipboardProxy.getFileSize(img)
         return size <= maxImgSizeBytes
     }