kci-gitlab: Introducing GitLab-CI Pipeline for Kernel Testing

This patch introduces a `.gitlab-ci` file along with a `ci/` folder,
defininga basic test pipeline triggered by code pushes to a GitLab-CI
instance. This initial version includes static checks (checkpatch and
smatch for now) and build tests across various architectures and
configurations. It leverages an integrated cache for efficient build
times and introduces a flexible 'scenarios' mechanism for
subsystem-specific extensions.

[ci: add prerequisites to run check-patch on MRs]
Co-developed-by: Tales Aparecida <tales.aparecida@redhat.com>
Signed-off-by: Tales Aparecida <tales.aparecida@redhat.com>
Signed-off-by: Helen Koike <helen.koike@collabora.com>

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Hey all,

You can check the validation of this patch on: https://gitlab.collabora.com/koike/linux/-/pipelines/86841

I would appreciate your feedback on this work, what do you think?

If you would rate from 0 to 5, where:

[ ] 0. I don't think this is useful at all, and I doubt it will ever be. It doesn't seem worthwhile.
[ ] 1. I don't find it useful in its current form.
[ ] 2. It might be useful to others, but not for me.
[ ] 3. It has potential, but it's not yet something I can incorporate into my workflow.
[ ] 4. This is useful, but it needs some adjustments before I can include it in my workflow.
[ ] 5. This is really useful! I'm eager to start using it right away. Why didn't you send this earlier? :)

Which rating would you select?