CD-18 Expose aws box url

@vasili-zolotov @d3ming 

This creates a link to the aws box that's created during ci. Right now it uses the users github icon as the button, but this can be changed later with a real icon. (I didn't want to take a stab at art)
I actually thought that this is supposed to be PL specific:
https://paperg.atlassian.net/browse/CD-18
Not all projects spin up devboxes, and there's no consistent way to determine if they do, so this is really only useful for PL.
Also the reason I exclude master and stable is because they change so frequently, it's not useful to use. It would rebuild before being able to test on it.