fix: update newsletter status on sending
fix: update newsletter status on sending

sets email_sent, schedule_send, and scheduled_to_send on newsletter
being sent

also switch to raw sql query to avoid default set by coalesce

Signed-off-by: Chinmay D. Pai <ab3234b32bd9ecd2892f3eb0b557ab584a8ff0cf@gmail.com>

almeidapaulopt/frappe,mhbu50/frappe,almeidapaulopt/frappe,adityahase/frappe,frappe/frappe,frappe/frappe,almeidapaulopt/frappe,saurabh6790/frappe,StrellaGroup/frappe,saurabh6790/frappe,adityahase/frappe,frappe/frappe,yashodhank/frappe,adityahase/frappe,saurabh6790/frappe,StrellaGroup/frappe,almeidapaulopt/frappe,yashodhank/frappe,mhbu50/frappe,mhbu50/frappe,yashodhank/frappe,StrellaGroup/frappe,saurabh6790/frappe,yashodhank/frappe,mhbu50/frappe,adityahase/frappe