Add support for Express

[timostamm]

This adds support for the web framework Express, in a similar fashion to Fastify, which was added in #474.

With the help of ConnectRouter:

// connect.ts
import { ConnectRouter } from "@bufbuild/connect";

export default function(router: ConnectRouter) {
  // implement rpc Say(SayRequest) returns (SayResponse)
  router.rpc(ElizaService, ElizaService.methods.say, async (req) => ({
    sentence: `you said: ${req.sentence}`,
  }));
}

... plugging services into an Express server becomes really straight-forward:

// server.ts
import http from "http";
import express from "express";
+ import routes from "connect";
+ import { expressConnectMiddleware } from "@bufbuild/connect-express";

const app = express();

+ app.use(expressConnectMiddleware({ 
+  routes 
+ }));

http.createServer(app).listen(8080);

Other changes:

• Fixes Way to recover from errors caused by non-compliant response body #469
• Runs Express and Fastify in the test suite packages/connect-node-test
• Fixes small mistakes in the Fastify README

[timostamm]

Defaults for acceptCompression moved a couple of lines up. Otherwise, createConnectRouter overrides with an empty array as a default, and these defaults never apply.

[timostamm]

We are adding all known content-types as string and as regex now. From the fastify docs:

Fastify first tries to match a content-type parser with a string value before trying to find a matching RegExp.

[timostamm]

We ran into #469 with fastify, which replies with an application/json content type for a HTTP 404 when application/json was sent.

The logic was changed to raise a ConnectError for the HTTP status code when parsing fails to fix the issue. This change is applied to the transports from @bufbuild/connect-web and @bufbuild/connect-node.