feat: enable rustls logging, gated by rustls-log feature flag

Author: crazyscot

Diff for: quinn-proto/Cargo.toml

@@ -30,6 +30,8 @@ ring = ["dep:ring"]
 platform-verifier = ["dep:rustls-platform-verifier"]
 # Configure `tracing` to log events via `log` if no `tracing` subscriber exists.
 log = ["tracing/log"]
+# Enable rustls logging
+rustls-log = ["rustls?/logging"]
 
 [dependencies]
 arbitrary = { workspace = true, optional = true }

Diff for: quinn/Cargo.toml

@@ -38,6 +38,8 @@ runtime-smol = ["async-io", "smol"]
 
 # Configure `tracing` to log events via `log` if no `tracing` subscriber exists.
 log = ["tracing/log", "proto/log", "udp/log"]
+# Enable rustls logging
+rustls-log = ["rustls?/logging"]
 
 [dependencies]
 async-io = { workspace = true, optional = true }