Add premade list of missing images

We have several images for which the UI guess the path and tries different paths until it found one that it can show. This is time consuming and takes a lot of requests. We can improve this in different ways:

1. **Easiest**: Provide a list alongside the language information with all paths that are known to be not existent on the server. This list is then added to the missing images list in the UI and it tries to load the default one if the requested one doesn't exist.
2. **More complex**: Let a tool (possibly `LangConv`) scan the image directory and create a lookup table for the resources and their respective images. This lookup table can then be delivered to the UI and it resolves the missing images with this information. This would also remove the need of checking multiple paths when displaying an image.