Add option to set Monday as first day of week

[abykovsk]

Added option to set Monday as first day of week

[mattpulver]

Thank you for the PR.

Few thoughts on this:

• In general we prefer to stay away from configuration options that produce different results. This makes it harder to debug query results from customers that may have different settings.
• There are other contexts of what it means to be the beginning of a week. For example EXTRACT(WEEK ...) has a separate meaning for what the first day of the week is, which remains unaffected, that this setting needs to be differentiated from in the --help message.
• This is replicated with EXTRACT(ISODOW FROM timestamp) - 1. Would this suffice?