Annotate multi-source factories

Doesn't do anything yet. Will add an annotation processor to do add info the repo JSON in the future.

buildSrc/src/main/kotlin/Deps.kt

@@ -0,0 +1,6 @@
+object Deps {
+    object kotlin {
+        const val version = "1.3.72"
+        const val stdlib = "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$version"
+    }
+}