Add image file previews

[slcw]

---

If this is your first feature request, read our contribution guidelines.

---

Pre-Submission checklist

• There is no existing issue that already asks for this feature.
  
• The feature already exists in rclone (on your PC or in Termux)
• I am prepared to help make this feature

What version of Round Sync are you using (About -> App version)?

Round Sync v2.5.5

What problem are you trying to solve?

When browsing files with the integrated file explorer, there are no file previews (thumbnail images). This makes managing image files difficult because it requires opening each file to determine the visual content of each file.

What should Round Sync be able to do differently to help with this problem?

Add image thumbnail previews to common image file formats (ie. jpg, png, gif, svg, ico, webp).

[Notmarrco]

is this a duplicate of #166 ?