Cache display names when checking for group name collisions.

app/src/main/java/org/thoughtcrime/securesms/database/NameCollisionTables.kt

@@ -521,6 +521,9 @@ class NameCollisionTables(
 
     val results = mutableListOf<ReviewRecipient>()
 
+    val cachedDisplayNames = HashMap<RecipientId, String>(members.size + changed.size)
+    val displayName = { recipient: Recipient -> cachedDisplayNames.getOrPut(recipient.id) { recipient.getDisplayName(context) } }
+
     for (reviewRecipient in changed) {
       if (results.contains(reviewRecipient)) {
         continue
@@ -528,8 +531,10 @@ class NameCollisionTables(
 
       members.remove(reviewRecipient.recipient)
 
+      val changedDisplayName = displayName(reviewRecipient.recipient)
+
       for (member in members) {
-        if (member.getDisplayName(context) == reviewRecipient.recipient.getDisplayName(context)) {
+        if (displayName(member) == changedDisplayName) {
           results.add(reviewRecipient)
           results.add(ReviewRecipient(member))
         }