Make secrets default to release-specific names

This changes the names of all of our Secrets to use .Release.Name in their name by default. All of the Secret names can be overridden using global.<chartish>.<secretdescriptor>.secret.

Prior to this the ability to customize the key name in the Secret wasn't consistent and it still isn't. I changed this in a couple of places that seemed to make sense. For example, I made secrets.yml in the rails secret static since that is a well known filename theoretically, but I added the option to change runner-registration-token since that is somewhat arbitrary. Not sure if it is worth examining these choices further in a different issue.

I also moved many of the templates from charts/gitlab/templates/ to templates/ because they are needed outside of the the gitlab sub-charts (e.g. minio). These were working because templates are global, but it seemed logically more correct to have templates defined at the highest level that encompasses all of their usage.

Closes #264 (closed)