API Key Access

[ShaneMcC]

It would be nice to be able to poke the API using an API Key of some kind (Eg for automated external tools manually triggering builds or bulk/automated configuration of build rules/push targets etc) rather than user/pass/2fa.

Probably easiest if there is a special end point that gives back a limited-time/access JWT or so then the rest of the API doesn't need to change.