Add Golang setup instructions for local debugging

The current contributor documentation for Argo CD — especially the Contributor QuickStart and Running Argo CD Locally guides — could be significantly improved to make it easier for new contributors to get started.

While resources like the [Running Argo CD Locally](https://argo-cd.readthedocs.io/en/stable/developer-guide/running-locally/) guide are helpful, contributors are often unsure whether to use make targets, goreman, or new tools like Tilt. Similarly, the current debugging documentation is focused on VS Code, and lacks guidance for popular alternatives like Goland.

Additionally, earlier efforts to include contribution steps in understand_the_basics.md received feedback about scope, structure, and placement. I believe a more appropriate and well-scoped enhancement would be to:

1. Clarify local development methods: Document and compare usage of make, goreman, and Tilt.
2. Improve debugging documentation: Add instructions for debugging in GoLand, alongside VS Code.
3. Refactor contributor content: Move and restructure earlier contribution guide content into the appropriate developer docs, not under understand_the_basics.md.
4. Include sign-off/DCO instructions: Clearly explain how to sign commits to comply with the DCO.
@nitishfy