Fix loading SQLite extensions

Fix loading SQLite extensions

* src/sqlite.c (sqlite3_db_config) [WINDOWSNT]: Load from the DLL.
(Fsqlite_load_extension): Use 'sqlite3_db_config' to enable and
disable loading of extensions.  Add a few free extensions to the
allow-list.  Fix testing for the ".dll" extension.  (Bug#63590)

* test/src/sqlite-tests.el (sqlite-load-extension): Fix the test
to require successful load if the extension does exist.