Save File Versioning #8027
Description
Is your feature request related to a problem? Please describe.
Related to #3150
Currently, we don't have a clean and unified pipeline of updating save files to new versions.
Supporting fully legacy data in save files until we're confident nobody needs it is wasteful and manual.
Describe the solution you'd like
We should link versions to save files.
We can then chain every updater from version_start->version_now without concern.
Save files are currently many small files, and so this might be awkward. As mentioned in the linked issue, this is especially bad for mapgen.
Additional context
We should ideally have these be separate script files squared away for organization purposes.
It would be nice to have a way of incorporating them into a PR as well.
Were we to do it that way, we would want to make the system pretty modular, so we don't do too much for a minor PR that needs a tiny adjustment to save data.
Additionally, we might consider making a script that "concatenates" all of a set for stable releases, so we don't wind up with too many files.
Conversely, we don't want one massive 40k line mega script you have to append to.