fix(frontend): sync folder for premium users (#3251)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

frontend/app/chat/[chatId]/components/ActionsBar/components/KnowledgeToFeed/components/FromConnections/FromConnections.tsx

@@ -118,7 +118,9 @@ export const FromConnections = (): JSX.Element => {
                       selectable={!!isPremium || currentProvider === "Notion"}
                       id={folder.id}
                       icon={folder.icon}
-                      isAlsoFile={currentProvider === "Notion"}
+                      isAlsoFile={
+                        currentProvider === "Notion" ? true : undefined
+                      }
                     />
                   </div>
                 ))}

frontend/app/chat/[chatId]/components/ActionsBar/components/KnowledgeToFeed/components/FromConnections/SyncElementLine/SyncElementLine.tsx

@@ -41,7 +41,7 @@ export const SyncElementLine = ({
 
   const [checked, setChecked] = useState<boolean>(initialChecked);
 
-  const showCheckbox: boolean = isAlsoFile ?? !isFolder;
+  const showCheckbox: boolean = isAlsoFile ?? selectable;
 
   const handleSetChecked = () => {
     setOpenedConnections((prevState) => {
@@ -82,11 +82,7 @@ export const SyncElementLine = ({
         }
       }}
     >
-      <div
-        className={`${styles.left} ${
-          !isAlsoFile && isFolder ? styles.folder : ""
-        }`}
-      >
+      <div className={`${styles.left} ${!showCheckbox ? styles.folder : ""}`}>
         {showCheckbox && (
           <div
             onMouseEnter={() => setIsCheckboxHovered(true)}