feat(ci): add GitLab CI pipeline with lint, build, and test stages

- Add `lint` stage using `pre-commit`
- Add `build` stage with Bazel clean/build, Python wheel creation, and 7 day artifact retention
- Add test stage with `test-cli` with JUnit reports and 7 day artifact retention

Signed-off-by: Deeptanshu Sekhri <deeptanshu.sekhri@arm.com>