Better type hinting for DoliDB

htdocs/core/db/Database.interface.php

htdocs/core/db/DoliDB.class.php

htdocs/core/db/mssql.class.php

htdocs/core/db/mysql.class.php

htdocs/core/db/mysqli.class.php

htdocs/core/db/pgsql.class.php

htdocs/core/db/sqlite.class.php

htdocs/core/db/sqlite3.class.php

htdocs/install/check.php

htdocs/install/etape1.php

htdocs/install/etape2.php

htdocs/install/etape4.php

htdocs/install/etape5.php

htdocs/install/repair.php

htdocs/install/upgrade.php

htdocs/install/upgrade2.php