[Feature] Support an ASEdgeLayoutSpec

[GeekTree0101]

It solves center alignment limitation on ASCornerLayoutSpec such as top/left/bottom/right

How to use

swift

let edgeSpec = ASEdgeLayoutSpec(child: baseNode, edge: edgeNode, location: .top)
edgeSpec.offset = 2.0

// or 

let edgeSpec2 = ASEdgeLayoutSpec(child: baseNode, edge: edgeNode, location: .top, offset: 2.0)

objective-c

ASEdgeLayoutSpec *edgeSpec = [ASEdgeLayoutSpec edgeLayoutSpecWithChild:baseNode
                                                                    edge:edgeNode
                                                                    location:ASEdgeLayoutLocationTop];
edgeSpec.offset = 2.0;

// or


ASEdgeLayoutSpec *edgeSpec = [ASEdgeLayoutSpec edgeLayoutSpecWithChild:baseNode
                                                                    edge:edgeNode
                                                                    location:ASEdgeLayoutLocationTop
                                                                    offset:2.0];

Screen shot

[CLAassistant]

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