Enhancements and refactorization

[metal3d]

This version could be RC

• use cobra to enhance command line experience (and to have completion)
• place const and vars on top of files
• fixing (patially) struct reordering

[github-actions[bot]]

:arrow_up: Go test coverage increased from 87.7% to 88.5% compared to 42304a6f990da4109f16171945d60d442eceaf30 Updated Package Coverages: ```diff # Package Name | Prior | New + github.com/metal3d/goreorder/ordering | 87.7% | 88.5% ```

View coverage for all packages

```diff # Package Name | Coverage + github.com/metal3d/goreorder/ordering | 88.5% ```