feat: add websocket upstream adapter

crates/crank-adapter-websocket/src/session.rs

@@ -0,0 +1,21 @@
+use std::time::Duration;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ReconnectPolicy {
+    pub max_attempts: u32,
+    pub backoff: Duration,
+}
+
+impl Default for ReconnectPolicy {
+    fn default() -> Self {
+        Self {
+            max_attempts: 0,
+            backoff: Duration::from_millis(0),
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct HeartbeatPolicy {
+    pub interval: Duration,
+}