this converts old QR codes to the new format, in an hacky, but simple
way, see #6518 for more details and for code snippet
then QR code change is esp. bad as ppl will have different versions for
some days at least, weakening overall UX, esp. of first-time-users that
may come to delta because of praised, seamless multidevice ... :)
i tested in https://github.com/deltachat/deltachat-ios/pull/2595 that
this actually fixes the problem, and there is no deeper issue with
changed chashes or so - seemed not to be the case, at least, with this
hack, core accepts QR codes from the released 1.52-and-before series
this hack gives user time to update, it can be removed after some months
(we can also remove the old BACKUP qr code alltogether then)
we should still not wait too long with the PR as there are already
versions out with the "new/bad" QR code (and growing, as new iOS
installations will get the new format, one cannot revert a version, only
pause rollout)
---------
Co-authored-by: link2xt <link2xt@testrun.org>
Restart the IO scheduler if needed to make the new config value effective (for `MvboxMove,
OnlyFetchMvbox, SentboxWatch` currently). Also add `set_config_internal()` which doesn't affect
running the IO scheduler. The reason is that `Scheduler::start()` itself calls `set_config()`,
although not for the mentioned keys, but still, and also Rust complains about recursive async calls.
