ci: Add baseline CI configuration

This commit adds the baseline CI configuration for the project. This
covers the "quality check" phase of the pipeline. During this phase, the
pre-commit checks are run, as well as other checks including GitLint and
TPIP.

In addition, documentation about the pre-commit hooks and
Towncrier is added. This describes the pre-commit hooks that are run by
the CI and how to run these checks locally.

Signed-off-by: Chuyue Luo <Chuyue.Luo@arm.com>