feat: add pipeline source and schedule name simulation capabilities

[xoro]

• Add --pipeline-source option supporting all 15 official GitLab CI sources
• Add --schedule-name option for testing specific schedule configurations
• Implement comprehensive validation and error handling
• Add constants-based validation with VALID_PIPELINE_SOURCES array
• Add complete test coverage and examples directory
• Update documentation with step-by-step getting started guide

Enables local testing of complex GitLab CI pipeline configurations including conditional logic, scheduled pipelines, and complex rules.

[firecow]

@xoro Holy christ, this is awesome work 😄

I'll probably be a few days with my review, but hang tight.

[xoro]

@firecow Thank you very much for your nice feedback. :-)
I am developing a DDNS server called FlyingDdns on GitLab:
https://gitlab.com/timopallach/FlyingDdns
I have a more or less complex pipeline setup and I heavily use the Gitlab CI include feature to "dynamically" build my pipeline scenario depending on the schedule and source.
I wanted to know if my pipeline breaks already in my pre commit hook so I tried several tool out there.
The most promising was gitlab-ci-local but it was missing these two small pieces I needed.

[xoro]

I just figured out that I have implemented an already existing functionality.
You could use the --variable option and pass the CI_* var like this:
gitlab-ci-local --variable CI_COMMIT_TAG=1.1.1 --list
gitlab-ci-local --variable CI_PIPELINE_SOURCE=schedule --variable SCHEDULE_NAME="Nightly Development Branch Build" --list

I therefor close the pr!
Sorry for the inconveniences!!! 🤦‍♂️