Allow setting sql_mode

[back-2-95]

If MySQL server has sql_mode which has ANSI or ANSI_QUOTES, it might results double quotes in dump file instead of backticks. And this might then break importing that dump back.

Always changing sql_mode on server side is not possible or it is for some other reason blocked.

If mysqldump-php would allow setting sql_mode, then developer using this library could go around the issue.

This is possible and I tested it by adding following to src/DumpSettings.php

$this->settings['init_commands'][] = "SET SESSION sql_mode='REAL_AS_FLOAT,PIPES_AS_CONCAT,IGNORE_SPACE,ONLY_FULL_GROUP_BY,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION,NO_ZERO_DATE,NO_ZERO_IN_DATE,STRICT_ALL_TABLES'";

See Smile-SA/gdpr-dump#145 for related discussion.

[back-2-95]

I was thinking how to set this. Maybe with ENV variable as it's not like a mysqldump option.