Basic support for resolving top-level SAM interfaces.

compiler/testData/loadJava/compiledJava/singleAbstractMethod/Runnable.java

@@ -0,0 +1,5 @@
+package test;
+
+public interface Runnable {
+    void run();
+}

compiler/testData/loadJava/compiledJava/singleAbstractMethod/Runnable.txt

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+package test
+
+public /*synthesized*/ fun Runnable(/*0*/ function : () -> jet.Unit) : test.Runnable
+
+public trait Runnable : java.lang.Object {
+    public abstract fun run() : jet.Unit
+}