add "After 90 days" option to disappearing messages

[adbenitez]

close #3437

[github-actions[bot]]

To test the changes in this pull request, install this apk: 📦 app-preview.apk

[link2xt]

Is this PR stuck?

Users keep asking on the forum https://support.delta.chat/t/more-options-for-disappearing-messages/3344/8

[adbenitez]

Is this PR stuck?

as "90 days" is quite arbitrary, I modify it to "1 year" which fits nicely and makes sense overall, but the core stock strings only expect weeks maximum, not even months, and shows "timer set to 52.1 weeks", so at least an "X months" string is needed

otherwise I could modify it to be something like 12 weeks or 52 weeks which might look a bit weird/arbitrary

cc @r10s

[adbenitez]

also, should we remove the first option (1 minute)? to keep the same amount of options

[adbenitez]

lgtm when the new stock strings are added and set

done, but we still need a new core release before this can be merged