fix: Improve performance list method (#153)

* fix: update ConversationV2 createdAt property

* remove test

* resolve comments

* Remove unused import statement

* fix lint issue

* Fix createdAt field name in Conversations data class

Author: Ezequiel Leanes

library/src/main/java/org/xmtp/android/library/ConversationV2.kt

@@ -30,6 +30,7 @@ data class ConversationV2(
     val context: Invitation.InvitationV1.Context,
     val peerAddress: String,
     val client: Client,
+    val createdAtNs: Long? = null,
     private val header: SealedInvitationHeaderV1,
 ) {
 
@@ -50,12 +51,13 @@ data class ConversationV2(
                 context = invitation.context,
                 peerAddress = peerAddress,
                 client = client,
+                createdAtNs = header.createdNs,
                 header = header,
             )
         }
     }
 
-    val createdAt: Date = Date(header.createdNs / 1_000_000)
+    val createdAt: Date = Date((createdAtNs ?: header.createdNs) / 1_000_000)
 
     /**
      * This lists messages sent to the [Conversation].

library/src/main/java/org/xmtp/android/library/Conversations.kt

@@ -226,6 +226,7 @@ data class Conversations(
                     context = data.invitation.context,
                     peerAddress = data.peerAddress,
                     client = client,
+                    createdAtNs = data.createdNs,
                     header = Invitation.SealedInvitationHeaderV1.getDefaultInstance(),
                 ),
             )