Keep anyone from modifying project base gitlab ci

Currently, for a project, i.e. Anchore Enterprise UI, we have outside contributors that could ostensibly inject any code that they wanted into a Gitlab CI file located in the root of that repo. For every project in https://repo1.dsop.io/dsop we would want to implement something like the following:

https://docs.gitlab.com/ee/ci/pipelines/settings.html#custom-ci-configuration-path

Parse existing Jenkinsfile to extract version, then parse Jenkinsfile if a plaintext file "version.txt" doesn't exist.