show minimized draft even for unchanged drafts

[ganthern]

As a user i expect that once my draft has been minimized that it will be always minimized again when opening it again so that i can always continue writing the draft.

AC:

• Opening a minimized draft and close it should minimize even no changes were made.
• Closing the mail editor without existing draft and without changes should not minimize.

Notes
We introduced this behavior because we do not want to store empty drafts, see:
#4105

We like to keep this behavior but once the draft has been saved the editor should be minimized. There are multiple solution how to deal with this but we decided for the solution that "If there's an existing draft, always minimize it when closing"

See refinement discussion in the wiki for more details.

[wrdhub]

Test Notes:

• Closing Empty Email will not result in saved draft or minimized draft
• Editing mail from Draft folder will result in minimized draft when closed
• Editing from minimized draft will result in minimized draft when closed