Code review comment for ~litios/ubuntu-security-tools:build-sources-list/use-auth-conf

Great improvement idd although the more I edit build-sources-list the more I feel it needs a bigger revamp.

In sec-buildenv I create esm-ppa.conf with permissions "640 root sudo" and I haven't encountered issues.

I also think it's a bit awkward to run sudo in the (now) new script but that's exactly what build-sources-list.install does at the moment.

I suggest having 3 scripts in total so that we also avoid duplicating things:

1) Have the new esm-auth-conf script simply output the right auth configuration and rename it to setup-esm-auth-conf

2) Have build-sources-list.install run both build-sources-list and esm-auth-conf and then install both source list and auth file. Maybe also rename it to something like setup-sources-list.

3) Remove sudo from build-sources-list.install, let if produce an error if it is not run with sudo

We would also need to update sec-buildenv and the wiki.

+ minor comments