Clean up or move away from using graphviz for component graph / pipeline's `.graph()` method

We currently use graphviz to generate our graphical representation of component graphs / pipelines.
https://github.com/alteryx/evalml/pull/2654 updated this representation to include X and y nodes and edges, but seems a little cluttered and potentially unclear (see PR for examples).

This issue tracks delving more into graphviz to see if we have more control over formatting the graph, or otherwise exploring other libraries that could give us a cleaner graph. For example, networkx is a graphing library that has [some drawing capabilities](https://networkx.org/documentation/stable/auto_examples/basic/plot_simple_graph.html) but I'm not sure how powerful they are.