templates: Add common templates

+ Remove old gitlab files for checks, we use templates from now on.

These include:

- gitlab pages publish
- gitlint
- license (+schema)
- pre-commit
- sync to public
- unittests

I created folders to be able to add scripts or other files that are
part of the templates. For instance gitlint requires python script.

Naming:
- template files are prefixed with `pipeline-`
- jobs that check (coding style, commit msg...) contain `-check` suffix
- variables must be in capital letters with proper suffix (_PATH, _DIR,
etc). We follow Gitlab variable names, check the default variables for
the proper naming
scheme

Requirement to not break this flow, we must introduce versioning for
this project.
Plus we rely on developer tools being submodule in all our projects.

Signed-off-by: Martin Kojtal <martin.kojtal@arm.com>