[Android][Kotlin] fixed build after decomission of jcenter and gradle update (#7840)

* [Android] fixed build after decomission of jcenter

JCenter[1] has been removed and now is failing android build. This
change updates the configuration to remove this and few other warnings.

1 - https://developer.android.com/studio/build/jcenter-migration

* [Kotlin] fix build for latest gradle version 8.0.1

---------

Co-authored-by: Derek Bailey <derekbailey@google.com>

android/app/build.gradle

@@ -1,15 +1,13 @@
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
-apply plugin: 'kotlin-android-extensions'
 
 android {
-  compileSdkVersion 30
-  buildToolsVersion "30.0.2"
+  compileSdk 33
 
   defaultConfig {
     applicationId "com.flatbuffers.app"
     minSdkVersion 26
-    targetSdkVersion 30
+    targetSdkVersion 33
     versionCode 1
     versionName "1.0"
 
@@ -113,13 +111,13 @@ android {
       dependsOn(generateFbsCpp)
     }
   }
+  namespace 'com.flatbuffers.app'
 }
 
 dependencies {
   implementation fileTree(dir: "libs", include: ["*.jar"])
   implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-  implementation 'androidx.core:core-ktx:1.3.2'
-  implementation 'androidx.appcompat:appcompat:1.2.0'
+  implementation 'androidx.appcompat:appcompat:1.6.1'
 
   // If you using java runtime you can add its dependency as the example below
   // implementation 'com.google.flatbuffers:flatbuffers-java:$latest_version'