Integrate gitlab-ci/yamllint

Commit: https://gitlab.com/SECO-Northern-Europe/yocto/infrastructure/gitlab-ci/-/commit/67f2fcae0c038ec5d1b1e92c2741bded89bc6333

yamllint: Add yamllint job to CI, add yamllint config

Add .yamllint.yml to configure the yamllint usage, should be used as master yamllint config from other stages also. Apply small changes to yml files to match yamllint.

BCS 746-000640