Upgrade icedove to 45.2.0-1

Originally created by @anonym on #11714 (Redmine)

Includes security fixes. Will also be needed for the fix of #11536 (closed).

Feature Branch: feature/11714-icedove-45.2.0-1

Edited May 15, 2020 by anonym

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information