move files/folders docs from UWP to WinUI

Author: jwmsft

hub/apps/develop/toc.yml

@@ -248,6 +248,28 @@ items:
           href: files/using-file-folder-pickers.md
         - name: "Tutorial: Save a file with a picker"
           href: files/pickers-save-file.md
+        - name: Enumerate and query files and folders
+          href: files/list-files-folders.md
+        - name: Create, write, and read a file
+          href: files/create-read-write-files.md
+        - name: Best practices for writing to files
+          href: files/best-practices-writing-files.md
+        - name: Get file properties
+          href: files/file-properties.md
+        - name: Determining availability of Microsoft OneDrive files
+          href: files/determine-availability-microsoft-onedrive-files.md
+        - name: Files and folders in the Music, Pictures, and Videos libraries
+          href: files/music-pictures-videos-libraries.md
+        - name: Thumbnail images
+          href: files/thumbnails.md
+        - name: Track recently used files and folders
+          href: files/track-recently-used-files-folders.md
+        - name: Track file system changes in the background
+          href: files/change-tracking-filesystem.md
+        - name: File access permissions
+          href: files/file-access-permissions.md
+        - name: Fast access to file properties in UWP
+          href: files/fast-file-properties.md
     - name: Devices and sensors
       items:
       - name: Overview

uwp/develop/toc.yml

@@ -194,36 +194,14 @@ items:
   - name: Files, folders, and libraries
     href: ../files/index.md
     items:
-    - name: Enumerate and query files and folders
-      href: ../files/quickstart-listing-files-and-folders.md
-    - name: Create, write, and read a file
-      href: ../files/quickstart-reading-and-writing-files.md
-    - name: Best practices for writing to files
-      href: ../files/best-practices-for-writing-to-files.md
-    - name: Get file properties
-      href: ../files/quickstart-getting-file-properties.md
     - name: Open files and folders with a picker
       href: ../files/quickstart-using-file-and-folder-pickers.md
     - name: Save a file with a picker
       href: ../files/quickstart-save-a-file-with-a-picker.md
     - name: Accessing HomeGroup content
       href: ../files/quickstart-accessing-homegroup-content.md
-    - name: Determining availability of Microsoft OneDrive files
-      href: ../files/quickstart-determining-availability-of-microsoft-onedrive-files.md
-    - name: Files and folders in the Music, Pictures, and Videos libraries
-      href: ../files/quickstart-managing-folders-in-the-music-pictures-and-videos-libraries.md
-    - name: Thumbnail images
-      href: ../files/thumbnails.md
-    - name: Track recently used files and folders
-      href: ../files/how-to-track-recently-used-files-and-folders.md
-    - name: Track file system changes in the background
-      href: ../files/change-tracking-filesystem.md
     - name: Access the SD card
       href: ../files/access-the-sd-card.md
-    - name: File access permissions
-      href: ../files/file-access-permissions.md
-    - name: Fast access to file properties in UWP
-      href: ../files/fast-file-properties.md
   - name: Machine Learning
     href: /windows/ai/
 - name: Deployment