Added displayName to be able to replace shortcut `productName ?: identifier` in application

BankingClientModel/src/commonMain/kotlin/net/codinux/banking/client/model/BankAccount.kt

@@ -2,6 +2,7 @@ package net.codinux.banking.client.model
 
 import kotlinx.datetime.LocalDate
 import kotlinx.datetime.LocalDateTime
+import net.codinux.banking.client.model.config.JsonIgnore
 import net.codinux.banking.client.model.config.NoArgConstructor
 
 @NoArgConstructor
@@ -35,5 +36,9 @@ open class BankAccount(
     var hideAccount: Boolean = false,
     var includeInAutomaticAccountsUpdate: Boolean = true
 ) {
+    @get:JsonIgnore
+    open val displayName: String
+        get() = productName ?: identifier
+
     override fun toString() = "$type $identifier $productName (IBAN: $iban)"
 }