Embed pymysql within the collection and use default test container

This change eliminates the need to install the connector on each
controlled node, as `pymysql` version 1.1.1 is now included. As a
result, we can safely assume its availability, thus simplifying the
testing process.

Also, I managed to remove the need for pre-built test containers. We
now use the default test containers from ansible-test.

plugins/module_utils/pymysql/optionfile.py

@@ -0,0 +1,21 @@
+import configparser
+
+
+class Parser(configparser.RawConfigParser):
+    def __init__(self, **kwargs):
+        kwargs["allow_no_value"] = True
+        configparser.RawConfigParser.__init__(self, **kwargs)
+
+    def __remove_quotes(self, value):
+        quotes = ["'", '"']
+        for quote in quotes:
+            if len(value) >= 2 and value[0] == value[-1] == quote:
+                return value[1:-1]
+        return value
+
+    def optionxform(self, key):
+        return key.lower().replace("_", "-")
+
+    def get(self, section, option):
+        value = configparser.RawConfigParser.get(self, section, option)
+        return self.__remove_quotes(value)