This patch improves numerous aspects on how the benchmarking
results are visualized:
 - rewrites the way HTML charts are generated, using a library (Chart.js)
 that's both easier to use and more visually pleasing.
 The new HTML page also now decouples data from the HTML itself,
 leading to faster load times and the ability to fetch data
 from remote sources.
 - The markdown output now contains a failures section that
 lists all benchmarks that failed for a given run. This will be
 a helpful for developers during PR testing.
 - Benchmarks can now have description that's displayed on the page.
 - And many more minor improvements.