fix: Refactor graph updating

[minghay]

Context

Updating an existing graph should be only need to consist of updating the metadata on the build status of nodes and edges and then updating the classes on the existing SVG.

Objective

1. Refactor the job node in the graph so that the event handler is on the SVG <g> element
2. Refactor the child element of the SVG <g> element so that the text and title are siblings for easier targeting and updating
3. Add in a utility function that can update the graph edge on an existing SVG graph
4. Add in a utility function that can update the graph node on an existing SVG graph
5. Refactor the V2 graph component to properly update the existing SVG graph as necessary

References

screwdriver-cd/screwdriver#3200

License

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