[TASK] Add Build/gitlab-ci.yml and includes

A first Build/gitlab-ci.yml for master. Core v10 and
v9 will have dedicated patches.

This specifies jobs executed via gitlab CI for master
pre-merge "a patch has been pushed" and nightly builds.

This uses a new testing infrastructure defined by
https://gitlab.typo3.org/core-testing/testing-infrastructure
to execute test suites.

Resolves: #93406
Releases: master
Change-Id: I377ac59478925b789f63871c8fa6c3b2d5b2a839
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67626


Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Simon Gilli <typo3@gilbertsoft.org>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Simon Gilli <typo3@gilbertsoft.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>