Add Benchmarks

[Lol3rrr]

Although this is not meant to be the fastest crate for rendering/displaying graphs, it would be nice to have some basic benchmarks to keep track of how it performs and maybe motivate some performance improvements, if needed, in the future. Especially for larger Graphs.

For a Start we could render a couple of differently sized graphs, with "random" layout, but with fixed seed, to see how it scales with larger Graphs and then maybe also take a look at some edge cases or potentially more complex graphs