Move autosave data into printer.autosave.cfg

[kageurufu]

Move autosave data from printer.cfg to printer.autosave.cfg

This no longer edits the user configuration commenting out duplicate options. Options in printer.autosave.cfg take priority over printer.cfg.

An automatic migration will take place the first SAVE_CONFIG after updating.

Thanks to @jwueller for the original implementation, I rewrote this as we decided to just bite the bullet and do everything at once. This superscedes #499

Checklist

• pr title makes sense
• added a test case if possible
• if new feature, added to the readme
• ci is happy and green

[gitdacat]

I saw in your implementation the original config in printer.cfg is not commented out.
This can be confusing when I want to change a config, edit printer.cfg, and found out there is no effect because it have been overridden.

[jwueller]

I didn't take a close look at it, but if my contribution is still used to some degree, I'd appreciate adding me as a co-author to the relevant commit(s):

Co-authored-by: Johannes Wüller <johanneswueller@gmail.com>

I'll leave judging whether that's appropriate to you, though! I'm glad this feature might finally make it in. I think it got stuck before because we couldn't quite figure out how to go about rolling it out.

Edit: @gitdacat Yes, I think commenting out the replaced options is important. It would lead to hard-to-debug behavior otherwise. Note that my version prioritizes user settings over autosaved ones, to ensure that it has predictable behavior. Hidden settings overriding explicit settings is a recipe for confusion.

[dalegaard]

I think auto-commenting should be removed, and instead the user can be told with a warning that they have specified a value and a different value is currently saved in autosave. Over time, we should move towards there existing no options that the user would want to both set manually and set with autosave.