Add filter filter on trigger

[SunBlack]

Currently on each new commit to a MR a pipeline will be triggered, even the build is not always required.

Example:

• Source code will be changed => Pipeline should be triggered
• Readme will be updated => No need to test the source code

Possibile solutions to retrieve changed files:

• Run a git diff with gitlabSourceBranch& gitlabTargetBranch => requires a checkout
• Use aggregated list of modified/added/deleted files from webhook

How to skip job

• Option 1) Add an API to retrieve and maybe filter the aggregated file list, so you can skip stages via when
• Option 2) Add a new trigger filter (similar to the combination of branchFilterType: 'NameBasedFilter' with includeBranchesSpec: '...')

Option 1 is more flexible, as you can e.g. skip some stages, but not all (e.g. run doxygen, but don't run tests). Option 2 has the benefit that a job can bypass the job queue, but requires to think also about what happens with the defined build within gitlabBuilds.

[Michaelxu2022]

"I hope to add a trigger based on the modification event of a specific file in the repo." example repo when the workspace file in the repo is updated."