Migrate from MySQLdb to PyMySQL (#40123)

* Migrate from MySQLdb to PyMySQL

* Deduplicate driver loading and failure message

* Explain requirements

* Apply requirements docs change to proxysql too

* Add changelog

lib/ansible/modules/database/mysql/mysql_db.py

@@ -67,7 +67,8 @@ requirements:
    - mysql (command line binary)
    - mysqldump (command line binary)
 notes:
-   - Requires the python-mysqldb package on the remote host, as well as mysql and mysqldump binaries.
+   - Requires the PyMySQL (Python 2.7 and Python 3.X) or MySQL-python (Python 2.X) package on the remote host,
+     as well as mysql and mysqldump binaries.
    - This module is B(not idempotent) when I(state) is C(import), and will import the dump file each time if run more than once.
 extends_documentation_fragment: mysql
 '''
@@ -107,16 +108,9 @@ import pipes
 import subprocess
 import traceback
 
-try:
-    import MySQLdb
-except ImportError:
-    mysqldb_found = False
-else:
-    mysqldb_found = True
-
 from ansible.module_utils.basic import AnsibleModule
 from ansible.module_utils.database import mysql_quote_identifier
-from ansible.module_utils.mysql import mysql_connect, mysqldb_found
+from ansible.module_utils.mysql import mysql_connect, mysql_driver, mysql_driver_fail_msg
 from ansible.module_utils._text import to_native
 
 
@@ -279,8 +273,8 @@ def main():
         supports_check_mode=True
     )
 
-    if not mysqldb_found:
-        module.fail_json(msg="The MySQL-python module is required.")
+    if mysql_driver is None:
+        module.fail_json(msg=mysql_driver_fail_msg)
 
     db = module.params["name"]
     encoding = module.params["encoding"]