DM drafted quantifiers after assignment automatically

[mattyg]

Currently, an administrator must first "Assign Quantifiers" for a period, then run the /admin-announce command via Discord to notify assigned quantifiers.

Instead, we could automatically send the DMs to notify quantifiers after they are assigned.

See original message below:

looks a bit complicated and easy to fat finger with all these variables you have to enter into a chat box. hopefully this doesn't get too complicated for non code-curious admins. Otherwise I would opt for some easy to use buttons for admins within the praise dashboard itself.

Originally posted by @divine-comedian in https://github.com/commons-stack/praise/issues/145#issuecomment-1071234198