Add tool for compositing localized text on top cover images

Notes:

1. Run sudo apt install jb imagemagick
2. You might need to edit the BASE_DIR variable for this to work on the renderfarm
3. It's based on the hi-res render produced by the renderfarm, so we will need to remove the episode titles from the SVG files and ensure we have a clean rerender before the text generation is applied.

Taking care of 3. will make the renderfarm very busy. Do you want me to create 1 branch per episode, so that you can merge them and rerender 1 by 1?

Read also note webcomics#86 (comment 715299) if you want to invest some time in the renderfarm.

Re. webcomics#86 (closed)

Depends on webcomics!556 (merged) and webcomics!558 (merged)

ETA: I have now tested everything non-Latin and found working fonts for Bengali & Hindi webcomics!561 (merged)