Profile Directory screen VoiceOver improvements

Add label to filter button (and change icon to match other filters)

Make each profile a single accessibility element

Tusker/Screens/Explore/FeaturedProfileCollectionViewCell.swift

@@ -123,4 +123,23 @@ class FeaturedProfileCollectionViewCell: UICollectionViewCell {
         }
     }
     
+    // MARK: Accessibility
+    
+    override var isAccessibilityElement: Bool {
+        get { true }
+        set {}
+    }
+    
+    override var accessibilityAttributedLabel: NSAttributedString? {
+        get {
+            guard let account else {
+                return nil
+            }
+            let s = NSMutableAttributedString(string: "\(account.displayName), ")
+            s.append(noteTextView.attributedText)
+            return s
+        }
+        set {}
+    }
+    
 }

Tusker/Screens/Explore/ProfileDirectoryViewController.swift

@@ -34,8 +34,9 @@ class ProfileDirectoryViewController: UIViewController {
 
         title = NSLocalizedString("Profile Directory", comment: "profile directory title")
         
-        // todo: it would be nice if there were a better "filter" icon
-        navigationItem.rightBarButtonItem = UIBarButtonItem(image: UIImage(systemName: "scope"), menu: nil)
+        let filterItem = UIBarButtonItem(image: UIImage(systemName: "line.3.horizontal.decrease.circle"), menu: nil)
+        filterItem.accessibilityLabel = "Filter"
+        navigationItem.rightBarButtonItem = filterItem
         updateFilterMenu()
         
         let layout = UICollectionViewCompositionalLayout(sectionProvider: { (sectionIndex, layoutEnvironment) in