When a user installs the ca-cert file from /pub on a satellite, part of what it does is go ahead and update rhsm.conf with the appropriate settings for eventual registration of client to satellite.  This is very convenient.

We should have a similar analogue when creating/using the certs tar.  

Pressently, after running `capsule-certs-generate` on Satellite, user is given a very long (and not easily pasteable) `capsule-installer` and associated string of flags, which includes various oauth keys/secrets parsed from locations across a sat6 install.

The RFE here is to  package the oauth credentials into the certs.tar and store it somewhere that can be retrieved during install. Just as we prepopulate rhsm.conf when doing katello ca cert, it seems it would be similarly useful to prepopulate this oauth stuff somewhere else, so user doesn't have to manually input on an install attempt.

Less stuff entered at install time = less room for error.