Merge branch 'rename_license_template_api' into 'master'

Rename Licenses API to License Templates API

## What does this MR do?

Earlier I renamed this in EE, thinking license templates was an EE-only feature. This backports that change to CE. Thanks to @vsizov for pointing out this error.

See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/400 for the EE merge request. 

See merge request !4957