fix: ChangePackage from packageName is part of the submodule dir name issue

ie:
```
submodule name: p1-core and ChangePackage from: p1.sub1-> to: p2.sub1

before this pr result ->  p2-core/src/java/sub1/xx
after  this pr result   -> p1-core/src/java/p2/sub1/xx
```

Author: qxo

rewrite-java/src/main/java/org/openrewrite/java/ChangePackage.java

@@ -259,10 +259,13 @@ public J postVisit(J tree, ExecutionContext ctx) {
                     String path = ((SourceFile) sf).getSourcePath().toString().replace('\\', '/');
                     String changingFrom = getCursor().getMessage(RENAME_FROM_KEY);
                     assert changingFrom != null;
-                    sf = ((SourceFile) sf).withSourcePath(Paths.get(path.replaceFirst(
-                            changingFrom.replace('.', '/'),
-                            changingTo.replace('.', '/')
-                    )));
+                    final int dirIdx = path.indexOf('/');
+                    final String newPath = path.substring(0, dirIdx) + path.substring(dirIdx)
+                            .replaceFirst(
+                                changingFrom.replace('.', '/'),
+                                changingTo.replace('.', '/')
+                            );
+                    sf = ((SourceFile) sf).withSourcePath(Paths.get(newPath));
 
                     for (J.Import anImport : sf.getImports()) {
                         if (anImport.getPackageName().equals(changingTo) && !anImport.isStatic()) {