Add extra features to the Test262 results representation

[Razican]

The new Test262 (ECMAScript test suite) representation lacks some nice to have features:

• A graph, maybe in a popover, to see the progress of the master branch commit by commit. The information is already available in the results.json file of the master branch, we just need to plot it.
• Add a third column in the top of the conformance website, showing all the versions that have Test262 results (v0.10 and above). This should be just a small square with the stats and a small icon to show the full results at the bottom.
• Loading spinner for Test262 conformance results #1644
• Retrieve feature-based results for Test262 runs #1645
• Detect "builtins" and extra features when running tests to be able to ignore them or present them better.
• Allow running tests by filtering those requiring a particular Built-in or feature (instead of filtering by test-suite).
• Add some links / information to explain how the Test262 works.
• Add a legend on what each thing means on the results.
• Show date along the X axis on the conformance chart boa-dev.github.io#149

[croraf]

If possible add a badge with current conformance percentage on the github main page, like:

[Razican]

Something else that's nice to have:

• Show compliance by feature (this requires a change in the results format).