Workflow diagram zoom

[Devessier]

What this PR adds

• Set a smaller size to the "+" button to create new steps
• Fit the flow in the view when the flow has been initialized by listening to the onInit event.
• Reset the Reactflow component instance when the current workflow version changes. This will re-trigger the onInit callback to re-fit the flow in the view.

Comments

We must call fitView in the onInit callback instead of relying on the fitView property of the Reactflow component because we rely on the first render of the nodes to measure their sizes and position the nodes with a layout algorithm, which corrupts the behavior of fitView.
The onInit callback seems to be called after the dimensions of the nodes have been measured and the nodes correctly positioned, which is the perfect timing to adjust the viewport.

Result

New

Old

Closes #7047