multi host configuration

In case we work with different gitlab instances, instead of having different config files, add the possibility to configure everything in one place and infer the server url from the git remote configuration (origin or specified)

git.itsufficient.me:
  remote: origin
  auth:
    id:
    secret:
    redirect-port:

git.grf.lan:
   remote: origin
   ca: grf-ca.crt
   auth:
     id:
     secret:
     redirect-port: