[PROPOSAL] Ensure automation on all repos that check license headers

[dblock]

What/Why

What are you proposing?

We have varying state of repos that check license headers. Do a campaign that will add license checkers in every repo in the org.

What users have asked for this feature?

We often merge features in various repos and I often have to comment that adding an ES license to new files is not needed for example.

What problems are you trying to solve?

Finding inconsistencies in license headers and fixing them manually.

What is the developer experience going to be?

Automation will ensure that all files in a repo have the right license headers, and ensure new code is checked in PRs for the same.

[dbwiddis]

+1 on automation of license headers.

It should generally be very straightforward ... a standard header for new files, or a specific exclusion if custom headers are needed.

Someone should address #98 authoritatively first, however.