Update android build configs (#534)

* Update compile sdk version
Update kotlin version

* Add missing HavenAccountList class to configure to be generated with haven.dart file

* Revert compile sdk and ndk changes

android/build.gradle

@@ -1,4 +1,5 @@
 buildscript {
+    ext.kotlin_version = '1.5.10'
     repositories {
         google()
         jcenter()
@@ -7,6 +8,7 @@ buildscript {
     dependencies {
         classpath 'com.android.tools.build:gradle:4.1.3'
         classpath 'com.google.gms:google-services:4.3.8'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
 

tool/configure.dart

@@ -433,6 +433,15 @@ abstract class MoneroSubaddressList {
   Future<void> setLabelSubaddress(Object wallet,
       {required int accountIndex, required int addressIndex, required String label});
 }
+
+abstract class HavenAccountList {
+  ObservableList<Account> get accounts;
+  void update(Object wallet);
+  void refresh(Object wallet);
+  List<Account> getAll(Object wallet);
+  Future<void> addAccount(Object wallet, {required String label});
+  Future<void> setLabelAccount(Object wallet, {required int accountIndex, required String label});
+}
   """;
 
   const havenEmptyDefinition = 'Haven? haven;\n';