JVM: Add more tests to jvm-abi-gen

plugins/jvm-abi-gen/testData/compare/syntheticAccessors/base/test.kt

@@ -0,0 +1,8 @@
+package test
+
+private val x = 1
+
+// We don't yet strip out empty top-level classes from the kotlin_module files!
+val y = 2
+
+object A { fun f() = x }