Refactor CompileKotlinAgainstCustomBinariesTest

Make all filenames start with lowercase letter (instead of half lower / half
upper)

compiler/testData/compileKotlinAgainstCustomBinaries/sameLibraryTwiceInClasspath/library-2/source.kt

@@ -0,0 +1,8 @@
+package testing
+
+object TopLevelObject
+
+class Outer {
+    inner class Inner
+    class Nested
+}