Add BlurHash placeholders at several places

* [ui] Added: Blurry previews of images before they are loaded

Also fixes a bug where ApiModel would remove items that already started
with a lowecase letter or didn't start with a letter at all.

core/src/jellyfinapimodel.cpp

@@ -183,6 +183,7 @@ QVariant ApiModel::data(const QModelIndex &index, int role) const {
     QJsonObject obj = m_array.at(index.row()).toObject();
 
     const QString &key = m_roles[role];
+
     if (obj.contains(key)) {
         return obj[key].toVariant();
     }

core/src/jsonhelper.cpp

@@ -30,7 +30,12 @@ void convertToCamelCase(QJsonValueRef val) {
             QJsonValueRef ref = obj[key];
             convertToCamelCase(ref);
             obj[convertToCamelCaseHelper(key)] = ref;
-            obj.remove(key);
+            if (key[0].isLower() || !key[0].isLetter()) {
+                obj[key] = ref;
+            } else {
+                obj[convertToCamelCaseHelper(key)] = ref;
+                obj.remove(key);
+            }
         }
         val = obj;
         break;