center domain story on import

[hofstef]

Is your feature request related to a problem? Please describe.
It's possible for users to drag the domain story out of the visible area of the canvas. While modeling, this is not a problem because the canvas is scrolled automatically while dragging. But after exported and later importing, the domain story will be outside of the visible area of the canvas. Users have to find the story on the infinite canvas and Egon does not support them. See example:

Describe the solution you'd like

• One solution is to center the domain story on import, so that it is in the visible area of the canvas. We head a half-hearted implemented that altered the x/y coordinates but not by enough. So I removed it after v2.3.0 was released. If think scrolling the canvas would be a better solution.
• Another solution would be to help users locate the domain story on the canvas - for example integrate diagram-js minimap. This could even help to prevent users from unintenionally moving their domain story out of the visible area of the canvas.