Display name of equity with strikeout font if the equity account has been closed.

Summary: Display name of equity with strikeout font if the equity account has been closed.

Test Plan:
Open Investment view.
Verify closed equity accounts are displayed with strike through font and open equity accounts are displayed with normal font.
Close an equity account.
Verify the display of the account just closed changed from normal to striked through font.
Reopen the equity account.
Verify the display of the account just reopened changed from striked through to normal font.

Reviewers: KMyMoney, tbaumgart

Reviewed By: KMyMoney, tbaumgart

Subscribers: KMyMoney

Tags: KMyMoney

Differential Revision: https://phabricator.kde.org/D16433