Optionally add EXIF tag to cards for better PMM integration

TCM should optionally write an EXIF tag to an image so that these can be queried by PMM (and maybe TCM in the future). It was decided to write `titlecard` at `0x4242` in the EXIF memoryspace.

For reference, the "fixed" EXIF tags are [here](https://exiftool.org/TagNames/EXIF.html).