[ADD] core: utility to easily enable logging on a cursor

Enabling sql logging for a specific section of code is currently a
pain in the ass as it requires updating both the cursor and the
logger. This utility does that.

This CM is *not* thread-safe as it updates and resets the cursor
without using CAS or anything, so if cursor 1 gets enabled, then
cursor 2, then cursor 1 stops, then cursor 2, cursor 2 will reset the
logger to `logging.DEBUG` which cursor 1 had set, rather than the
probable `logging.NOTSET` it originally was.

Should be possible to fix by e.g. storing the levels in a static
stack (and setting whatever gets popped) buuut... the logging is
already a bit of a mess when multithreaded so I'm unsure it matters
much.

Part-of: odoo/odoo#76243

odoo/sql_db.py

@@ -371,6 +371,21 @@ class Cursor(BaseCursor):
         self.sql_log_count = 0
         self.sql_log = False
 
+    @contextmanager
+    def _enable_logging(self):
+        """ Forcefully enables logging for this cursor, restores it afterwards.
+
+        Updates the logger in-place, so not thread-safe.
+        """
+        previous, self.sql_log = self.sql_log, True
+        level = _logger.level
+        _logger.setLevel(logging.DEBUG)
+        try:
+            yield
+        finally:
+            _logger.setLevel(level)
+            self.sql_log = previous
+
     @check
     def close(self):
         return self._close(False)