Move common gradle config into convention plugins.

image-editor/app/build.gradle

@@ -1,44 +1,17 @@
 plugins {
-    id 'com.android.application'
-    id 'kotlin-android'
+    id 'signal-sample-app'
     id 'kotlin-kapt'
 }
 
 android {
     namespace 'org.signal.imageeditor.app'
 
-    compileSdk COMPILE_SDK
-
     defaultConfig {
         applicationId "org.signal.imageeditor.app"
-        versionCode 1
-        versionName "1.0"
-        multiDexEnabled true
-
-        minSdk MINIMUM_SDK
-        targetSdk TARGET_SDK
-    }
-
-    buildTypes {
-        release {
-            minifyEnabled false
-            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
-        }
-    }
-    compileOptions {
-        sourceCompatibility JAVA_VERSION
-        targetCompatibility JAVA_VERSION
-    }
-    kotlinOptions {
-        jvmTarget = '1.8'
     }
 }
 
 dependencies {
-    implementation libs.androidx.core.ktx
-    implementation libs.androidx.appcompat
-    implementation libs.material.material
-    implementation project(':core-util')
     implementation project(':image-editor')
 
     implementation libs.glide.glide

image-editor/app/src/test/java/com/example/imageeditor/app/ExampleUnitTest.kt

@@ -1,9 +1,8 @@
 package com.example.imageeditor.app
 
+import org.junit.Assert.assertEquals
 import org.junit.Test
 
-import org.junit.Assert.*
-
 /**
  * Example local unit test, which will execute on the development machine (host).
  *
@@ -14,4 +13,4 @@ class ExampleUnitTest {
   fun addition_isCorrect() {
     assertEquals(4, 2 + 2)
   }
-}
+}