fix android plugin not found

Author: tmthecoder

dargon2_flutter/dargon2_flutter/example/android/settings.gradle

@@ -9,3 +9,17 @@ localPropertiesFile.withReader("UTF-8") { reader -> properties.load(reader) }
 def flutterSdkPath = properties.getProperty("flutter.sdk")
 assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
 apply from: "$flutterSdkPath/packages/flutter_tools/gradle/app_plugin_loader.gradle"
+
+def flutterProjectRoot = rootProject.projectDir.parentFile.toPath()
+
+def plugins = new Properties()
+def pluginsFile = new File(flutterProjectRoot.toFile(), '.flutter-plugins')
+if (pluginsFile.exists()) {
+    pluginsFile.withReader('UTF-8') { reader -> plugins.load(reader) }
+}
+
+plugins.each { name, path ->
+    def pluginDirectory = flutterProjectRoot.resolve(path).resolve('android').toFile()
+    include ":$name"
+    project(":$name").projectDir = pluginDirectory
+}