Moved current incremental compiler test data into subdirectory.

Tweaked test generator to avoid creating test methods for parent directory of tests.

jps-plugin/testData/incremental/pureKotlin/classSignatureChanged/build.log

@@ -0,0 +1,13 @@
+Cleaning output files:
+out/production/module/test/Klass.class
+End of files
+Compiling files:
+src/class.kt
+End of files
+Cleaning output files:
+out/production/module/test/TestPackage-usage-*.class
+out/production/module/test/TestPackage.class
+End of files
+Compiling files:
+src/usage.kt
+End of files

jps-plugin/testData/incremental/pureKotlin/classSignatureChanged/class.kt

@@ -0,0 +1,5 @@
+package test
+
+class Klass {
+    fun foo() = ":)"
+}

jps-plugin/testData/incremental/pureKotlin/classSignatureChanged/class.kt.new

@@ -0,0 +1,5 @@
+package test
+
+class Klass {
+    fun foo() = 123
+}

jps-plugin/testData/incremental/pureKotlin/classSignatureChanged/usage.kt

@@ -0,0 +1,5 @@
+package test
+
+fun usage(a: Klass) {
+    a.foo()
+}