Add Campaign Endpoints to API

[willselby]

Story

https://www.notion.so/Ability-to-create-campaigns-via-the-API-2ca60ecd7c8448d7bca29e0fdab65758

Description

Enable interaction with campaigns via API.

[dljfield]

I think we actually need to consider a bit more about what we want the API to be able to do around campaigns. The normal CRUD parts that we implement in other endpoints and that we have here is only part of the story with them, allowing us to use the API to get to the point of what we consider Draft status, but not going any further.

So we need to consider whether we want the API to be able to dispatch campaigns or not, and if they are dispatched, what stats we want to actually expose. Right now the GET endpoints expose some data but not all of the stats that we expose in the UI, I think, and some of that is maybe irrelevant to Draft campaigns.

My own view is that the create/update endpoints need to handle every field except scheduled_at, and then have a separate endpoint to dispatch. Additionally, we should either include stats in the index/show views or include none of the things like sent/open/click counts and instead have a separate stats endpoint for a campaign.

[JonoB]

Yeah, I was thinking about this as well.

As it currently stands, just setting the campaign status to 2 will result in it being dispatched (as long as a the scheduled_at is in the past).