tests-httpd: basic infra to run curl against an apache httpd plus nghttpx for h3

- adding '--with-test-httpd=<path>' to configure non-standard apache2
  install
- python env and base classes for running httpd
- basic tests for connectivity with h1/h2/h3
- adding test cases for truncated responses in http versions.
- adding goaway test for HTTP/3.
- adding "stuttering" tests with parallel downloads in chunks with
  varying delays between chunks.

- adding a curltest module to the httpd server, adding GOAWAY test.
    - mod_curltest now installs 2 handlers
      - 'echo': writing as response body what came as request body
      - 'tweak': with query parameters to tweak response behaviour
- marked known fails as skip for now

Closes #10175

tests/tests-httpd/conftest.py

@@ -0,0 +1,81 @@
+#***************************************************************************
+#                                  _   _ ____  _
+#  Project                     ___| | | |  _ \| |
+#                             / __| | | | |_) | |
+#                            | (__| |_| |  _ <| |___
+#                             \___|\___/|_| \_\_____|
+#
+# Copyright (C) 2008 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# This software is licensed as described in the file COPYING, which
+# you should have received as part of this distribution. The terms
+# are also available at https://curl.se/docs/copyright.html.
+#
+# You may opt to use, copy, modify, merge, publish, distribute and/or sell
+# copies of the Software, and permit persons to whom the Software is
+# furnished to do so, under the terms of the COPYING file.
+#
+# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+# KIND, either express or implied.
+#
+# SPDX-License-Identifier: curl
+#
+###########################################################################
+#
+import logging
+import os
+import sys
+from typing import Optional
+
+import pytest
+
+sys.path.append(os.path.join(os.path.dirname(__file__), '.'))
+
+from testenv import Env, Nghttpx, Httpd
+
+
+def pytest_report_header(config, startdir):
+    return f"curl tests-httpd tests"
+
+
+def pytest_addoption(parser):
+    parser.addoption("--repeat", action="store", type=int, default=1,
+                     help='Number of times to repeat each test')
+
+
+def pytest_generate_tests(metafunc):
+    if "repeat" in metafunc.fixturenames:
+        count = int(metafunc.config.getoption("repeat"))
+        metafunc.fixturenames.append('tmp_ct')
+        metafunc.parametrize('repeat', range(count))
+
+
+@pytest.fixture(scope="package")
+def env(pytestconfig) -> Env:
+    env = Env(pytestconfig=pytestconfig)
+    level = logging.DEBUG if env.verbose > 0 else logging.INFO
+    logging.getLogger('').setLevel(level=level)
+    env.setup()
+    return env
+
+
+@pytest.fixture(scope='package')
+def httpd(env) -> Httpd:
+    httpd = Httpd(env=env)
+    assert httpd.exists(), f'httpd not found: {env.httpd}'
+    httpd.clear_logs()
+    assert httpd.start()
+    yield httpd
+    httpd.stop()
+
+
+@pytest.fixture(scope='package')
+def nghttpx(env) -> Optional[Nghttpx]:
+    if env.have_h3_server():
+        nghttpx = Nghttpx(env=env)
+        nghttpx.clear_logs()
+        assert nghttpx.start()
+        yield nghttpx
+        nghttpx.stop()
+    return None
+