j2k: flatten test cases and testData directory structure

Move j2k/test/tests -> j2k/tests, j2k/test/testData -> j2k/testData

j2k/testData/fileOrElement/varArg/ellipsisTypeSeveralParams.java

@@ -0,0 +1,2 @@
+//method
+String format(String pattern, Object... arguments);

j2k/testData/fileOrElement/varArg/ellipsisTypeSeveralParams.kt

@@ -0,0 +1 @@
+fun format(pattern: String, vararg arguments: Any): String

j2k/testData/fileOrElement/varArg/ellipsisTypeSingleParams.java

@@ -0,0 +1,2 @@
+//method
+void pushAll(Object... objs) {}

j2k/testData/fileOrElement/varArg/ellipsisTypeSingleParams.kt

@@ -0,0 +1,2 @@
+fun pushAll(vararg objs: Any) {
+}