Added maven-checkstyle-plugin to parent POM for code style checks

- Integrate Checkstyle to enforce coding standards across modules.
- Ensure Checkstyle applies to both dmi-service and dmi-stub modules.
- Fixed all code check style issues.

Issue-ID: CPS-2461
Change-Id: Ie84928c1f2e3de549cc8fab2001974369884a831
Signed-off-by: sourabh_sourabh <sourabh.sourabh@est.tech>
5 files changed