Update `api` header to support `site` and `from`

[nathanclevenger]

We need site to be the domain if it is .do but if it's a preview domain (*.dev.driv.ly) or localhost, then we need site to be whatever the current root domain (like workflows or functions, etc) with a default of workflows at /sites/workflows.do

We also need to add from which on a normal domain should be https://dotdo.ai but if it's a preview domain or localhost then it should go to /sites

[linear]

ENG-439 Update `api` header to support `site` and `from`