This PR has no issue. I got this cool idea and decided to quickly try it out, and it works.

### Summary

This will allow Flutter Developers to have less code in their Android Gradle buildscripts.

```diff
 plugins {
     id "com.android.application"
     id "dev.flutter.flutter-gradle-plugin"
     id "kotlin-android"
 }

-def localProperties = new Properties()
-def localPropertiesFile = rootProject.file("local.properties")
-if (localPropertiesFile.exists()) {
-    localPropertiesFile.withReader("UTF-8") { reader ->
-        localProperties.load(reader)
-    }
-}
-
-def flutterVersionCode = localProperties.getProperty("flutter.versionCode")
-if (flutterVersionCode == null) {
-    flutterVersionCode = "1"
-}
-
-def flutterVersionName = localProperties.getProperty("flutter.versionName")
-if (flutterVersionName == null) {
-    flutterVersionName = "1.0"
-}
-
-def keystorePropertiesFile = rootProject.file("keystore.properties")
-def keystoreProperties = new Properties()
-
 keystoreProperties.load(new FileInputStream(keystorePropertiesFile))

 android {
         applicationId "pl.baftek.discoverrudy"
         minSdk 21
         targetSdk 34
-        versionCode flutterVersionCode.toInteger()
-        versionName flutterVersionName
+        versionCode flutter.versionCode()
+        versionName flutter.versionName()
     }
```

The boilerplate that loads 'local.properties' can live in Flutter Gradle Plugin.

### Concerns

I was worried about lifecycle/ordering issues, so I tested it.

To Flutter Gradle Plugin, I added:

```diff
 class FlutterPlugin implements Plugin<Project> {
     //...

     @Override
     void apply(Project project) {
+        project.logger.quiet("Start applying FGP")
         // ...
     }
 }
```

and to my `android/app/build.gradle` I added:

```diff
 android {
+    logger.quiet("Start evaluating android block")
     namespace "pl.bartekpacia.awesomeapp"
     compileSdk 34
 
     defaultConfig {
         applicationId "pl.baftek.discoverrudy"
         minSdk 21
         targetSdk 34
         versionCode flutter.versionCode()
         versionName flutter.versionName()
     }
```

Gradle first applies the plugins (which sets versionCode and versionName on FlutterExtension), and then it executes the `android {}` extension block:

```
$ ./gradlew :app:assembleDebug

> Configure project :app
Start applying FGP
Start evaluating android block

BUILD SUCCESSFUL in 2s
383 actionable tasks: 10 executed, 373 up-to-date
```

So ordering is fine.