Move importsDumper to compiler plugin

plugins/imports-dumper/testData/simpleCase/c/C1.kt

@@ -0,0 +1,16 @@
+package c
+
+import a.A1
+import a.A2
+import b.B1.Companion.a2
+import b.nestedB.bar
+import b.nestedB.foo
+
+class C1 {
+    val x = foo(TODO())
+    val y = bar(TODO())
+
+    val z: A1? = null
+    val t: A2? = a2
+
+}

plugins/imports-dumper/testData/simpleCase/c/JavaC.java

@@ -0,0 +1,13 @@
+package c;
+
+import a.A1;
+import b.B1;
+import b.nestedB.B2Kt;
+
+public class JavaC {
+    private void doStuff() {
+        C1 c1 = new C1();
+        B1 b1 = new B1();
+        B2Kt.bar(new A1());
+    }
+}