Add tower-h2 and more macro

tower-h2/src/error.rs

@@ -0,0 +1,12 @@
+pub(crate) fn reason_from_dyn_error(err: &(dyn std::error::Error + 'static)) -> h2::Reason {
+    let mut cause = Some(err);
+    while let Some(err) = cause {
+        if let Some(h2_err) = err.downcast_ref::<h2::Error>() {
+            return h2_err.reason().unwrap_or(h2::Reason::INTERNAL_ERROR);
+        }
+        cause = err.source();
+    }
+
+    // unknown error
+    h2::Reason::INTERNAL_ERROR
+}