Rename package jet -> kotlin in ant

org.jetbrains.jet.buildtools.ant -> org.jetbrains.kotlin.ant

The old antlib.xml is kept for migration purposes

compiler/testData/integration/ant/js/sourceMap/build.log.expected

@@ -0,0 +1,10 @@
+OUT:
+Buildfile: [TestData]/build.xml
+
+build:
+[kotlin2js] Compiling [[TestData]/root1] => [[Temp]/out.js]
+
+BUILD SUCCESSFUL
+Total time: [time]
+
+Return code: 0

compiler/testData/integration/ant/js/sourceMap/build.xml

@@ -0,0 +1,7 @@
+<project name="Ant Task Test" default="build">
+  <taskdef resource="org/jetbrains/kotlin/ant/antlib.xml" classpath="${kotlin.lib}/kotlin-ant.jar"/>
+
+  <target name="build">
+    <kotlin2js src="${test.data}/root1" noStdlib="true" output="${temp}/out.js" sourcemap="true"/>
+  </target>
+</project>

compiler/testData/integration/ant/js/sourceMap/root1/foo.kt

@@ -0,0 +1,3 @@
+package foo
+
+fun box(): String = "OK"