Cache all types, add benchmark_bson.py + EVG tests

- Add create_rust_extension_tasks() and create_rust_extension_variants() to generate_config.py
- Test Rust extension on Linux (RHEL8), macOS ARM64, and Windows
- Test with Python 3.10, 3.12, and 3.14 across different topologies
- Add PR task for Python 3.10 on standalone to run on every PR
- Create install-rust.sh script to install Rust toolchain and maturin
- Update setup-tests.sh to install Rust when PYMONGO_BUILD_RUST is set
- Add RUST_TESTING.md documentation explaining the test setup
- Generated tasks run full BSON test suite with PYMONGO_USE_RUST=1

Author: aclark4life