bpo-38193: Add http.client script

[jaswdr]

Adding http.client script.

Examples:

Handling JSON response:

$ ./python -m http.client https://httpbin.org/json
HTTP/1.1 200 OK
Date: Thu, 17 Jun 2021 19:14:38 GMT
Content-Type: application/json
Content-Length: 429
Connection: keep-alive
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true

{
  "slideshow": {
    "author": "Yours Truly",
    "date": "date of publication",
    "slides": [
      {
        "title": "Wake up to WonderWidgets!",
        "type": "all"
      },
      {
        "items": [
          "Why <em>WonderWidgets</em> are great",
          "Who <em>buys</em> WonderWidgets"
        ],
        "title": "Overview",
        "type": "all"
      }
    ],
    "title": "Sample Slide Show"
  }
}

Handling binary response:

$ ./python -m http.client https://httpbin.org/brotli
HTTP/1.1 200 OK
Date: Thu, 17 Jun 2021 19:15:14 GMT
Content-Type: application/json
Content-Length: 164
Connection: keep-alive
Server: gunicorn/19.9.0
Content-Encoding: br
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true

1bda00001c07ced93cc8c13c0587a0cf06cf918f335f62d72efa1344a42f1592a8e03f77db091f98dcdbdf6e0b5a0b83200ae3dc234bb7f9081e227a6881ac820ee9e8f9a3fa3ede7502f758c25acff5006f54b09e62aae86b28a657cd0e20da9a48eef17dcf5a38146957898aeddbd1400c54abf463fd4b18d2b4a95d2f3992a2eb84d51d6d2bd389c64a26b4925a035c9a30082aed2fc585bc1d8a6341b16fc64deb03

Writing response to file:

$ ./python -m http.client https://httpbin.org/brotli -o out.brotli
HTTP/1.1 200 OK
Date: Thu, 17 Jun 2021 19:15:55 GMT
Content-Type: application/json
Content-Length: 164
Connection: keep-alive
Server: gunicorn/19.9.0
Content-Encoding: br
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true

1bda00001c07ceb93cc8c19be010f4d9e2b6d49f45318b74cd3b6a091244a42f14e03f77db091f98dcdbdfda82d6c22088c220ca3d91749b8fe021a29015c82ae8908e9e3fc17dbceb84eeb184b59ef341be51c17a8aa990afa118be72768451d644e71adff704e15024bb1a926ddf4e0a203ac95ba51eeb3712c4e606bcde06e238bd911c94ecedd618cf121e340e8d3835611094db5f8a0b79db2c4915a7be3adeb436

$ file out.brotli
out.brotli: data
$ ls -lh out.brotli
-rw-r--r-- 1 jaswdr jaswdr 164 Jun 17 19:15 out.brotli

https://bugs.python.org/issue38193

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[MaxwellDupre]

Could you check why one test is failing?