Add support of auto folded directories (#7674)

Added support of auto collapsed directories, for example when directory
has only one directory inside we should display it as dir1/dir2 (#6935
). Please feel free to propose better solutions, as I am new in Rust

Demo:
https://streamable.com/seo3n9

Release Notes:

- Added support for auto-collapsing directories.

assets/settings/default.json

@@ -187,7 +187,10 @@
     // Whether to reveal it in the project panel automatically,
     // when a corresponding project entry becomes active.
     // Gitignored entries are never auto revealed.
-    "auto_reveal_entries": true
+    "auto_reveal_entries": true,
+    /// Whether to fold directories automatically
+    /// when directory has only one directory inside.
+    "auto_fold_dirs": true
   },
   "collaboration_panel": {
     // Whether to show the collaboration panel button in the status bar.