Reinstate Proguard/R8 (#5134)

* Reinstate Proguard/R8

According to APK analyzer
Before: 18044 classes with 113387 methods in 3 dex files
After: 12604 classes with 68010 methods in 2 dex files
APK download size is reduced by 2.8 MB

* Add debug build type without R8

app/build.gradle.kts

@@ -55,20 +55,27 @@ android {
         named("debug") {
             versionNameSuffix = "-${getCommitCount()}"
             applicationIdSuffix = ".debug"
+
+            isShrinkResources = true
+            isMinifyEnabled = true
+            proguardFiles("proguard-android-optimize.txt", "proguard-rules.pro")
+        }
+        create("debugFull") { // Debug without R8
+            initWith(getByName("debug"))
+            isShrinkResources = false
+            isMinifyEnabled = false
         }
         named("release") {
-            /*named("postprocessing") {
-                postprocessing {
-                    isObfuscate = false
-                    isOptimizeCode = true
-                    isRemoveUnusedCode = false
-                    isRemoveUnusedResources = true
-                }
-                setProguardFiles(listOf(getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"))
-            }*/
+            isShrinkResources = true
+            isMinifyEnabled = true
+            proguardFiles("proguard-android-optimize.txt", "proguard-rules.pro")
         }
     }
 
+    sourceSets {
+        getByName("debugFull").res.srcDirs("src/debug/res")
+    }
+
     flavorDimensions("default")
 
     productFlavors {
@@ -76,9 +83,6 @@ android {
             buildConfigField("boolean", "INCLUDE_UPDATER", "true")
             dimension = "default"
         }
-        create("fdroid") {
-            dimension = "default"
-        }
         create("dev") {
             resConfigs("en", "xxhdpi")
             dimension = "default"