This endpoint starts an authorization flow that lets an Observe user generate an
authorization token to use for external tools and scripts. This token will have
the same powers as the user authorizing, and can be passed in the
Authorization: Bearer <customerid> <apitoken> header of requqests.
This endpoint will return with a URL that the user should visit in a web browser
to allow the token creation; that URL will lead to a page that requires the user
to be logged in (through whatever password or SSO mechanism the user normally uses.)
The response from this endpoint also includes a "serverToken" field, which is a
token that can be used to poll the tenant for the status of the token creation, and
if successful, will return the issued access key.
Essentially, this endpoint implements the Oauth "device" authorization flow.