Support single Java source files in kotlinc arguments

E.g. "kotlinc foo.kt test/Bar.java" will compile foo.kt, and
declarations from Bar.java will be accessible to Kotlin code in foo.kt.

The change in AbstractTopLevelMembersInvocationTest is needed because an
incorrect configuration was created in that test where a library jar was
also a Java source root (the compiler is never configured this way in
production), which led to an exception in
JavaCoreProjectEnvironment#addSourcesToClasspath

 #KT-17697 Fixed

compiler/testData/cli/jvm/singleJavaFileRoots/DefaultPackage.java

@@ -0,0 +1 @@
+public class DefaultPackage {}