Upgrade Ktor library to version 2.x

We are still on 1.6 and going to v2 now before release makes the mailbox more future proof and the webserver easier to upgrade in the future.

added Sponsor 6 Weight: 5 labels

assigned to @grote

mentioned in merge request !107 (merged)

added S: in code review label

removed Weight: 5 label

added Weight: 3 label

closed with merge request !107 (merged)

mentioned in commit a7ba7612

added R: fixed label and removed S: in code review label

added Mailbox Mailbox app labels

added T: task label