Add support for customizing topic names via a convention.

[jplaisted]

Requested by a few people in OS.

Companies probably need to pick _ or . as a delimiter and we hard coded _

TODO to finish the implmentation for v5. For right now v5 is LI only and unfinished. Getting this in for v4 so it is useful to other companies now.

TODO BEFORE SUBMIT - make configurable via spring
TODO BEFORE SUBMIT - decide if this needs to be an internal RB first
TODO BEFORE SUBMIT - see where else we can use this (jobs, where else?)

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable)

[jplaisted]

I probably won't pull this in, I'll have to submit internally I think*, just using it for discussion.

*we don't have a great pull mechanism right now, but I'm working on fixing that :)