Add ability for running pipelines for subprojects.

Problem to solve

I have a repo with two projects(frontend, backend) and gitlab-ci in them. I want to run two pipelines from each repository like if thay will be different repositories.

Intended users

This feature will be used when need contain many different projects in one repository(Yes, I know about git submodules, but the customer wants everything to be in one.

Further

Proposal

Add a new parameter to gitlab-ci script language like build_subproject which will be run a pipeline with also changed working directory.

Permissions and Security

Documentation

Testing

What does success look like, and how can we measure that?

Links / references