Let the Yoga sample app compile

Summary:
The sample app is really old and has a lot of legacy code. Here I'm refreshing it a bit.
Will do another pass later (perhaps rewrite it in Kotlin?).

Reviewed By: mdvacca

Differential Revision: D45694414

fbshipit-source-id: 36a84609b0dcf5b4a5237da900f665e4eb7895a5

settings.gradle.kts

@@ -7,8 +7,10 @@
 
 plugins { id("com.gradle.enterprise").version("3.7.1") }
 
-include(":yoga", ":yoga-layout")
+include(":sample", ":yoga", ":yoga-layout")
+
 project(":yoga").projectDir = file("java")
+
 project(":yoga-layout").projectDir = file("android")
 
 rootProject.name = "yoga-github"
@@ -17,4 +19,4 @@ rootProject.name = "yoga-github"
 // you can configure your custom Gradle Enterprise instance
 if (file("./gradle/gradle-enterprise.gradle.kts").exists()) {
   apply(from = "./gradle/gradle-enterprise.gradle.kts")
-}
+}