http2: make response.end() return this

doc/api/http2.md

@@ -2617,11 +2617,16 @@ See [`response.socket`][].
 #### response.end([data][, encoding][, callback])
 <!-- YAML
 added: v8.4.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/18780
+    description: This method now returns a reference to `ServerResponse`.
 -->
 
 * `data` {string|Buffer}
 * `encoding` {string}
 * `callback` {Function}
+* Returns: {this}
 
 This method signals to the server that all of the response headers and body
 have been sent; that server should consider this message complete.

lib/internal/http2/compat.js

@@ -596,6 +596,8 @@ class Http2ServerResponse extends Stream {
       this[kFinish]();
     else
       stream.end();
+
+    return this;
   }
 
   destroy(err) {

test/parallel/test-http2-compat-serverrequest-end.js

@@ -26,7 +26,7 @@ server.listen(0, common.mustCall(function() {
 
         server.close();
       }));
-      response.end();
+      assert.strictEqual(response.end(), response);
     }));
   }));