HTTP/2 Connection Coalescing support

[indiedeveloperGPU]

Hi, first of all great work on this library — it's by far the most complete Python HTTP client for low-level fingerprint emulation.

One behavior that's currently missing for accurate OkHttp (and general mobile client) emulation is HTTP/2 connection coalescing: when multiple hostnames resolve to the same IP and share a TLS certificate (e.g. wildcard or SAN), a real OkHttp client reuses the existing HTTP/2 connection instead of opening a new TCP/TLS handshake for each host.

This is specified in RFC 7540 §9.1.1 and is actively implemented in OkHttp's ConnectionPool. Without it, even a perfectly emulated SETTINGS frame + JA3/JA4 fingerprint can be detected via connection graph anomalies — multiple TLS handshakes where a real client would have one.

Would it be feasible to expose a coalescing-aware connection pool in wreq/rnet? Even a basic implementation (reuse existing H2 connection if IP matches and cert SAN covers the new host) would close a significant gap for mobile client emulation.

Happy to provide pcap examples showing the exact behavior if useful.