Make it possible to show corretly if the localstore job is running.

Summary:
Otherwise you see key details are requested the whole time.

test is we there are valid keydata in the mime content.

hasKey is not used anymore

always show keydetails from mimepart

show if key is unknown.

add test for showSignuatureDetails

Subscribers: #kde_pim

Tags: #kde_pim

Differential Revision: https://phabricator.kde.org/D8949