Add deauthorize comfirmation dialog

[typebrook]

#1534

When user click on OAuth preference option and OSM account is authorized,
ask if user want to deauthorize it. If not, just do OAuth.

[westnordost]

Cool, thank you! I have a few comments, but I will just do this myself after the merge. Particularly, I want to change:

• translation is done in POEditor and then always pulled from there. Will push the new strings to POEdtior and then edit in your strings.
• first time I see takeIf in action. Though, in this case, I have the opinion that it does not increase readability (rather the contrary), I'll rather use a simple if-else here.
• I will remove the string oauth_confirm_deauthroize_username. Since every string needs to be translated into 20+ languages, I weigh for every string if it is necessary
• I want to improve the English wording

[typebrook]

weigh for every string if it is necessary
readability

Good points! I'll take care of these rules next time.
Have a nice day!

[westnordost]

You too!