Support regen-app-ni for read-only app (#301)

Support regen-app-ni for read-only app (#301)

When a partial update of tizenfx occurs, native image files of application created with FNV option  must be regenerated.
However, it is not possible with the current implementation to replace the native-image files of the app installed in the read-only area like the preload app.
To solve this problem, add a functionality that creates new native images under /opt/usr/dotnet/apps, when creating a new native image files of read-only app.