Pyre (https://pyre-check.org/) is being replaced with Pyrefly (https://pyrefly.org/). The latter was added to the conformance suite in #2080.

This PR:

• Removes Pyre infrastructure and results from conformance/.
• Replaces references to Pyre in the docs and README with Pyrefly. I also took the opportunity to remove references to Pytype, which was officially deprecated and removed from conformance earlier this year.
• Regenerates the conformance results: https://htmlpreview.github.io/?https://raw.githubusercontent.com/rchen152/typing/afc8de9bea0983a3b781157af8b428f8608135d1/conformance/results/results.html.