feat: implements a common way to print session log of a request

* This is implemented for pipe, tcp, rustls and kawa-h1 logs

Signed-off-by: Florentin Dubois <florentin.dubois@clever-cloud.com>

lib/src/lib.rs

@@ -339,7 +339,7 @@ pub mod https;
 use std::{
     cell::RefCell,
     collections::{BTreeMap, HashMap},
-    fmt,
+    fmt::{self, Display, Formatter},
     net::SocketAddr,
     rc::Rc,
     str,
@@ -850,6 +850,20 @@ pub struct Readiness {
     pub interest: Ready,
 }
 
+impl Display for Readiness {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        let i = &mut [b'-'; 4];
+        let r = &mut [b'-'; 4];
+        let mixed = &mut [b'-'; 4];
+
+        display_ready(i, self.interest);
+        display_ready(r, self.event);
+        display_ready(mixed, self.interest & self.event);
+
+        write!(f, "I({:?})&R({:?})=M({:?})", String::from_utf8_lossy(i), String::from_utf8_lossy(r), String::from_utf8_lossy(mixed))
+    }
+}
+
 impl Default for Readiness {
     fn default() -> Self {
         Self::new()