Vendor API connection code from Docker SDK for Python (#398)

* Vendor parts of the Docker SDK for Python

This is a combination of the latest git version
(https://github.com/docker/docker-py/tree/a48a5a9647761406d66e8271f19fab7fa0c5f582)
and the version before Python 2.7 support was removed
(https://github.com/docker/docker-py/tree/650aad3a5fb84059b392ad450f760ed08143ae3f),
including some modifications to work with Ansible module_utils's
system (i.e. third-party imports are guarded, and errors are
reported during runtime through a new exception
MissingRequirementException).

* Create module_utils and plugin_utils for working with the vendored code.

The delete call cannot be called delete() since that method already exists from requests.

* Vendor more code from Docker SDK for Python.

* Adjust code from common module_utils.

* Add unit tests from Docker SDK for Python.

* Make test compile with Python 2.6, but skip them on Python 2.6.

* Skip test that requires a network server.

* Add changelog.

* Update changelogs/fragments/398-docker-api.yml

Co-authored-by: Brian Scholer <1260690+briantist@users.noreply.github.com>

* Minimum API version is 1.25.

Co-authored-by: Brian Scholer <1260690+briantist@users.noreply.github.com>

plugins/module_utils/_api/utils/json_stream.py

@@ -0,0 +1,88 @@
+# -*- coding: utf-8 -*-
+# This code is part of the Ansible collection community.docker, but is an independent component.
+# This particular file, and this file only, is based on the Docker SDK for Python (https://github.com/docker/docker-py/)
+#
+# Copyright (c) 2016-2022 Docker, Inc.
+#
+# It is licensed under the Apache 2.0 license (see Apache-2.0.txt in this collection)
+
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+import json
+import json.decoder
+
+from ansible.module_utils.six import text_type
+
+from ..errors import StreamParseError
+
+
+json_decoder = json.JSONDecoder()
+
+
+def stream_as_text(stream):
+    """
+    Given a stream of bytes or text, if any of the items in the stream
+    are bytes convert them to text.
+    This function can be removed once we return text streams
+    instead of byte streams.
+    """
+    for data in stream:
+        if not isinstance(data, text_type):
+            data = data.decode('utf-8', 'replace')
+        yield data
+
+
+def json_splitter(buffer):
+    """Attempt to parse a json object from a buffer. If there is at least one
+    object, return it and the rest of the buffer, otherwise return None.
+    """
+    buffer = buffer.strip()
+    try:
+        obj, index = json_decoder.raw_decode(buffer)
+        rest = buffer[json.decoder.WHITESPACE.match(buffer, index).end():]
+        return obj, rest
+    except ValueError:
+        return None
+
+
+def json_stream(stream):
+    """Given a stream of text, return a stream of json objects.
+    This handles streams which are inconsistently buffered (some entries may
+    be newline delimited, and others are not).
+    """
+    return split_buffer(stream, json_splitter, json_decoder.decode)
+
+
+def line_splitter(buffer, separator=u'\n'):
+    index = buffer.find(text_type(separator))
+    if index == -1:
+        return None
+    return buffer[:index + 1], buffer[index + 1:]
+
+
+def split_buffer(stream, splitter=None, decoder=lambda a: a):
+    """Given a generator which yields strings and a splitter function,
+    joins all input, splits on the separator and yields each chunk.
+    Unlike string.split(), each chunk includes the trailing
+    separator, except for the last one if none was found on the end
+    of the input.
+    """
+    splitter = splitter or line_splitter
+    buffered = text_type('')
+
+    for data in stream_as_text(stream):
+        buffered += data
+        while True:
+            buffer_split = splitter(buffered)
+            if buffer_split is None:
+                break
+
+            item, buffered = buffer_split
+            yield item
+
+    if buffered:
+        try:
+            yield decoder(buffered)
+        except Exception as e:
+            raise StreamParseError(e)