Fix not being able to share images from Shortcuts actions that have public.image and public.file-url representations

Closes #420

ShareExtension/ShareViewController.swift

@@ -79,7 +79,14 @@ class ShareViewController: UIViewController {
         var attachments: [DraftAttachment] = []
         
         for itemProvider in inputItem.attachments ?? [] {
-            if let attached: NSURL = await getObject(from: itemProvider) {
+            // attachments have the highest priority, but only given this heuristic
+            // otherwise attachment decoding ends up being overzealous
+            let likelyAttachment = [UTType.image, .movie].contains(where: { itemProvider.hasItemConformingToTypeIdentifier($0.identifier) })
+            
+            if likelyAttachment,
+               let attachment: DraftAttachment = await getObject(from: itemProvider) {
+                attachments.append(attachment)
+            } else if let attached: NSURL = await getObject(from: itemProvider) {
                 if url == nil {
                     url = attached as URL
                 }
@@ -87,8 +94,6 @@ class ShareViewController: UIViewController {
                 if text.isEmpty {
                     text = s as String
                 }
-            } else if let attachment: DraftAttachment = await getObject(from: itemProvider) {
-                attachments.append(attachment)
             }
         }