title: play-services-ads conflicts with appcompat
body: <p>When I add <code>implementation 'com.google.android.gms:play-services-ads:18.2.0'</code> to my build.gradle, Android Studio highlights <code>implementation 'com.android.support:appcompat-v7:28.0.0'</code> with the error:</p>
  
  <pre><code>Dependencies using groupId com.android.support and androidx.* can not be combined but found IdeMavenCoordinates{myGroupId='com.android.support', myArtifactId='versionedparcelable', myVersion='28.0.0', myPacking='aar', myClassifier='null'} and IdeMavenCoordinates{myGroupId='androidx.interpolator', myArtifactId='interpolator', myVersion='1.0.0', myPacking='aar', myClassifier='null'} incompatible dependencies
  </code></pre>
  
  <p>My build.gradle is:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  apply plugin: 'kotlin-android'
  
  apply plugin: 'kotlin-android-extensions'
  
  android {
      compileSdkVersion 28
      configurations.all {
          resolutionStrategy.force 'com.android.support:appcompat-v7:28.0.0'
      }
      defaultConfig {
          applicationId "com.XXXXXX.XXXXXX"
          minSdkVersion 14
          targetSdkVersion 28
          versionCode 3
          versionName "1.1.2"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
      implementation 'com.android.support:appcompat-v7:28.0.0'
      implementation 'com.android.support.constraint:constraint-layout:1.1.3'
      implementation 'com.google.android.gms:play-services-ads:18.2.0'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.2'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
  }
  
  </code></pre>