Added showing coordinates when using Move Tool.

Coordinates showing in floating message in format: X: x px, Y: y px.
X, Y means position of Left Top pixel of the moved area.
Also there are two spin bars, which you can use for setting image
position by keyboard (not only arrows).

Reviewers: #krita, dkazakov
Subscribers: dkazakov, scottpetrovic, timotheegiet, Deevad
Differential Revision: https://phabricator.kde.org/D2238
BUG:143306
Auditors: #krita_manual