Fix deprecated gradle BuildConfig warning (#6648)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/1210715540682696/task/1211122564014100?focus=true

### Description
Fixes gradle deprecation warning around enabling BuildConfig for the
project.

This is no longer a project-wide config, but per module. 
Previously, all modules had a BuildConfig.java file generated even if
they didn't read any config.
Now only the modules that actually access BuildConfig have it enabled.

### Steps to test this PR
Verify that correct values are used at runtime based on the build config
and build variant.

Test case 1:

- [x] Clean install of internalDebug
- [x] Check that you see the "Skip onboarding" button
- [x] Check that all pixels have "test=1" 
- [x] Search for generated BuildConfig.java files, there should be 7
(for each module that has it enabled)
- [x] Open them and verify correct config (DEBUG=true,
BUILD_TYPE="internal", ...)

Test case 2:

- [x] Clean install of playRelease
- [x] Check that you don't see the "Skip onboarding" button
- [x] Open
app/build/generated/source/buildConfig/internal/debug/com/duckduckgo/app/browser/BuildConfig.java
and verify correct config
- [x] Search for generated BuildConfig.java files, there should be 7
(for each module that has it enabled)
- [x] Open them and verify correct config (DEBUG=false,
BUILD_TYPE="release", ...)

### UI changes
No UI changes

Author: landomen

app/build.gradle

@@ -72,6 +72,7 @@ android {
     }
     buildFeatures {
         viewBinding = true
+        buildConfig = true
     }
     compileOptions {
         coreLibraryDesugaringEnabled = true

autofill/autofill-impl/build.gradle

@@ -123,6 +123,9 @@ android {
     compileOptions {
         coreLibraryDesugaringEnabled = true
     }
+    buildFeatures {
+        buildConfig = true
+    }
     defaultConfig {
         if (project.hasProperty("$autofillDisableAuthRequirementBuildFlag")) {
             buildConfigField "boolean", "AUTH_REQUIRED", "false"
@@ -146,4 +149,4 @@ tasks.register('installForAutofillTesting', Exec) {
 tasks.register('autofillTestLocal', Exec) {
     commandLine 'maestro', 'test', '--include-tags', 'autofillNoAuthTests,autofillPasswordGeneration,autofillBackfillingUsername', "$rootDir/.maestro"
     dependsOn 'installForAutofillTesting'
-}
+}

build.gradle

@@ -189,4 +189,4 @@ fladle {
     }
 }
 
-apply plugin: 'android-reporting'
+apply plugin: 'android-reporting'

gradle.properties

@@ -21,6 +21,5 @@ org.gradle.caching=true
 org.gradle.parallel=true
 org.gradle.configureondemand=true
 org.gradle.configuration-cache=true
-android.defaults.buildfeatures.buildconfig=true
 android.nonFinalResIds=false
 

malicious-site-protection/malicious-site-protection-impl/build.gradle

@@ -101,6 +101,9 @@ android {
     compileOptions {
         coreLibraryDesugaringEnabled = true
     }
+    buildFeatures {
+        buildConfig = true
+    }
     defaultConfig {
         buildConfigField "String", "MALICIOUS_SITE_PROTECTION_AUTH_TOKEN", "\"${MALICIOUS_SITE_PROTECTION_AUTH_TOKEN}\""
     }

network-protection/network-protection-impl/build.gradle

@@ -112,10 +112,13 @@ android {
             includeAndroidResources = true
         }
     }
+    buildFeatures {
+        buildConfig = true
+    }
     defaultConfig {
         buildConfigField "String", "NETP_DEBUG_SERVER_TOKEN", "\"${NETP_DEBUG_SERVER_TOKEN}\""
     }
     compileOptions {
         coreLibraryDesugaringEnabled = true
     }
-}
+}

privacy-config/privacy-config-internal/build.gradle

@@ -56,6 +56,10 @@ android {
     }
     namespace 'com.duckduckgo.privacy.config.internal'
 
+    buildFeatures {
+        buildConfig = true
+    }
+
     defaultConfig {
         def patchFiles = getConfigPatchFiles()
         def patchFileNames = []
@@ -163,4 +167,4 @@ afterEvaluate {
 
     // force the task to always run (never up-to-date)
     copyConfigPatches.outputs.upToDateWhen { false }
-}
+}

statistics/statistics-impl/build.gradle

@@ -99,4 +99,7 @@ android {
     compileOptions {
         coreLibraryDesugaringEnabled = true
     }
+    buildFeatures {
+        buildConfig = true
+    }
 }

statistics/statistics-impl/src/main/java/com/duckduckgo/app/statistics/api/PixelService.kt

@@ -17,8 +17,8 @@
 package com.duckduckgo.app.statistics.api
 
 import com.duckduckgo.anvil.annotations.ContributesNonCachingServiceApi
+import com.duckduckgo.app.statistics.BuildConfig
 import com.duckduckgo.common.utils.AppUrl
-import com.duckduckgo.common.utils.BuildConfig
 import com.duckduckgo.di.scopes.AppScope
 import io.reactivex.Completable
 import retrofit2.http.GET

sync/sync-impl/build.gradle

@@ -121,6 +121,9 @@ android {
     compileOptions {
         coreLibraryDesugaringEnabled = true
     }
+    buildFeatures {
+        buildConfig = true
+    }
     defaultConfig {
         if (project.hasProperty("$syncDisableAuthRequirementBuildFlag")) {
             buildConfigField "boolean", "AUTH_REQUIRED", "false"