Feature: Add Multi-Architecture Docker Build Support

🔖 Feature description

We need to update the Docker build pipeline for cmd-nsc-init to support multi-architecture image builds, specifically for linux/amd64 and linux/arm64 platforms.

🎤 Pitch

**Why This Matters ?**

- Enables usage of the image on ARM-based environments (e.g., Raspberry Pi, AWS Graviton, Apple M-series).
- Aligns with ongoing multi-arch compatibility efforts across all KubeSlice repositories.
- Improves flexibility and adoption across diverse environments.

✌️ Solution

**Acceptance Criteria:**

- Dockerfile updated to support cross-platform builds.
- Confirm compatibility by testing on at least one linux/arm64 environment.

**Suggested Steps:**

- Update Dockerfile for cross-architecture compatibility. refer to [https://github.com/kubeslice/kubeslice-controller/blob/master/Dockerfile](Dockerfile example) to understand how it is done in other KubeSlice repos
- Enable Docker Buildx in the CI workflow (i.e GitHub Actions)
- Test locally or in CI to validate builds for both amd64 and arm64.
- (optional) Create a Makefile to build images