MAINTENANCE: Improve build scripts

* Upgrade gradle to `5.6.4`
* Upgrade android gradle plugin to `3.5.2`
* Upgrade support library version to `28.0.0`
* Upgrade LibGDX to `1.9.10`
  * This should fix some warnings with calls to graylisted functions
* Upgrade checkstyle to `8.26`
* Upgrade kotlin gradle plugin to `1.3.60`
* Move `fabric.properties` to a template file and generate it from buildscript
* Fix some kotlin warnings
* Remove obsolete property from `gradle.properties`
* Upgrade fabric gradle plugin to fix some warnings
* Upgrade `detekt` to a stable version (was RC before)
  * Update detekt config from default config, migrate `test-pattern` excludes
* Move androidemulators specific configuration into a separate file
* Group ext variables into one block
* Move `detekt` configuration into `code_quality_tasks`
* Create a `copyGoogleServicesFile` function to improve readability
* Simplify flavor declaration
  * Group `buildConfigField` properties
  * Move `buildConfigField` properties into the default configuration and overwrite in flavors
  * Remove unused `FEATURE_CLOUD_MESSAGING_ENABLED` build config field
* Add dependency to `copyAndroidNatives` as done in the libGDX example gradle file

Author: Thomas Schwengler

.gitignore

@@ -60,6 +60,7 @@ __pycache__
 
 #api-keys
 catroid/google-services.json
+catroid/fabric.properties
 
 #Crowdin folder
 crowdin/

build.gradle

@@ -24,7 +24,7 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
-    ext.kotlin_version = '1.3.10'
+    ext.kotlin_version = '1.3.60'
     repositories {
         google()
         jcenter()
@@ -33,7 +33,7 @@ buildscript {
     dependencies {
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
-        classpath 'com.android.tools.build:gradle:3.5.0'
+        classpath 'com.android.tools.build:gradle:3.5.2'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         classpath 'com.dicedmelon.gradle:jacoco-android:0.1.4'
         classpath 'org.catrobat.gradle.androidemulators:android-emulators-gradle:1.6.2'

catroid/build.gradle

@@ -30,9 +30,6 @@
   <module name="TreeWalker">
     <property name="tabWidth" value="4" />
 
-    <!-- To enable SuppressWithNearbyCommentFilter -->
-    <module name="FileContentsHolder" />
-
     <!-- Annotations -->
     <module name="AnnotationLocation">
       <property name="allowSamelineMultipleAnnotations" value="false" />
@@ -172,8 +169,10 @@
     <module name="ImportOrder">
       <property name="option" value="bottom" />
       <property name="groups" value="android,com,cucumber,edu,junit,net,org,java,javax" />
+      <property name="staticGroups" value="android,com,cucumber,edu,junit,net,org,java,javax" />
       <property name="ordered" value="true" />
       <property name="separated" value="true" />
+      <property name="separatedStaticGroups" value="true" />
     </module>
     <module name="RedundantImport" />
     <module name="PackageDeclaration" />
@@ -230,6 +229,17 @@
       <property name="ignoreComments" value="true" />
       <property name="message" value="Spaces aren't allowed for indentation. Tabs only" />
     </module>
+
+    <module name="SuppressWithNearbyCommentFilter">
+      <property name="commentFormat" value="CHECKSTYLE DISABLE ([\w\|]+) FOR (-?\d+) LINES" />
+      <property name="checkFormat" value="$1" />
+      <property name="influenceFormat" value="$2" />
+    </module>
+
+    <module name="SuppressionCommentFilter">
+      <property name="offCommentFormat" value="@formatter\:off" />
+      <property name="onCommentFormat" value="@formatter\:on" />
+    </module>
   </module>
 
   <module name="NewlineAtEndOfFile">
@@ -289,17 +299,6 @@
     <property name="message" value="Use ellipses character … instead of &amp;#8230;." />
   </module>
 
-  <module name="SuppressWithNearbyCommentFilter">
-    <property name="commentFormat" value="CHECKSTYLE DISABLE ([\w\|]+) FOR (-?\d+) LINES" />
-    <property name="checkFormat" value="$1" />
-    <property name="influenceFormat" value="$2" />
-  </module>
-
-  <module name="SuppressionCommentFilter">
-    <property name="offCommentFormat" value="@formatter\:off" />
-    <property name="onCommentFormat" value="@formatter\:on" />
-  </module>
-
   <module name="SuppressionFilter">
     <property name="file" value="catroid/config/checkstyle_suppressions.xml" />
   </module>