Improve realization and logic in command entry's prompt item animations.

 - Disable background colour manipulation
 - Set colour for Queued status similar to another statuses.
 - Change animation realization: from QTimer to QPropertyAnimation: simpler and convenient

Also disable setting queued status for expression, which we run immediatly

This commit also fix problem with QPropertyAnimation warnings (in short: we start animation, and immideatly remove animated object in qDeleteAll, of couse before animation finished)

Differential Revision: https://phabricator.kde.org/D15487