Backport of PRs to stable-2 (#251)

* Allow the "%" character in database name (#227)

The naming rules for MySQL/MariaDB identifiers, when quoted, allow the
`%` character.

However, currently, the use of the `%` character in database names
results in mismatch or missing databases.

- Rewrite query to identify the databases in the catalog using
  `information_schema` instead of `SHOW DATABASES LIKE`
- Escape the `%` character in `CREATE DATABASE` query.

Signed-off-by: Nicolas Payart <npayart@gmail.com>
(cherry picked from commit 6b12435b2b)

* mysql_db: Fix assert in tests suite (#239)

Signed-off-by: Nicolas Payart <npayart@gmail.com>
(cherry picked from commit 5522e45284)

* mysql_db: Improve tests (#240)

- Define variables "db_names" and "db_formats" in defaults
- Use of the "vars" option in includes instead of default parameters
  that might be overridden by a previous task
- Use of the "loop" option in includes instead of duplicating include
  tasks
- Use a nested loop on db_names and db_formats in state_dump_import test

Signed-off-by: Nicolas Payart <npayart@gmail.com>
(cherry picked from commit e4de13aabe)

* MAINTAINERS file: Add new maintainer (#248)

(cherry picked from commit d411a8e216)

Co-authored-by: Nicolas PAYART <koleo@users.noreply.github.com>

plugins/modules/mysql_db.py

@@ -330,7 +330,7 @@ executed_commands = []
 def db_exists(cursor, db):
     res = 0
     for each_db in db:
-        res += cursor.execute("SHOW DATABASES LIKE %s", (each_db.replace("_", r"\_"),))
+        res += cursor.execute("SELECT SCHEMA_NAME FROM information_schema.SCHEMATA WHERE SCHEMA_NAME = %s", (each_db,))
     return res == len(db)
 
 
@@ -519,7 +519,8 @@ def db_create(cursor, db, encoding, collation):
     query_params = dict(enc=encoding, collate=collation)
     res = 0
     for each_db in db:
-        query = ['CREATE DATABASE %s' % mysql_quote_identifier(each_db, 'database')]
+        # Escape '%' since mysql cursor.execute() uses a format string
+        query = ['CREATE DATABASE %s' % mysql_quote_identifier(each_db, 'database').replace('%', '%%')]
         if encoding:
             query.append("CHARACTER SET %(enc)s")
         if collation: