Teach index working with source roots with package prefix

#KT-9167 Fixed

Original commit: 23e35ab112

jps/jps-plugin/testData/general/SourcePackageLongPrefix/module2/src/module2.kt

@@ -0,0 +1,13 @@
+package some
+
+import bad.prefix.KotlinTestInBadPrefix
+import good.prefix.KotlinTestInGoodPrefix
+import good.prefix.JavaTest;
+import test.JavaRef
+
+val goodTest = KotlinTestInGoodPrefix()
+val badTest = KotlinTestInBadPrefix()
+val javaTest = JavaTest().bar()
+val javaRef = JavaRef().foo(null)
+
+

jps/jps-plugin/testData/general/SourcePackageLongPrefix/module2/src/test/JavaRef.java

@@ -0,0 +1,9 @@
+package test;
+
+import good.prefix.JavaTest;
+
+public class JavaRef {
+    public void foo(JavaTest javaTest) {
+        
+    }
+}