ProfileModel: add follows helper

This will be used for "Follows You" logic

damus/Models/ProfileModel.swift

@@ -20,6 +20,24 @@ class ProfileModel: ObservableObject, Equatable {
     var sub_id = UUID().description
     var prof_subid = UUID().description
     
+    func follows(pubkey: String) -> Bool {
+        guard let contacts = self.contacts else {
+            return false
+        }
+        
+        for tag in contacts.tags {
+            guard tag.count >= 2 && tag[0] == "p" else {
+                continue
+            }
+            
+            if tag[1] == pubkey {
+                return true
+            }
+        }
+        
+        return false
+    }
+    
     func get_follow_target() -> FollowTarget {
         if let contacts = contacts {
             return .contact(contacts)