Add support for .env.ecample

What problem will this feature address?

Each time I add a new environment variable to my project and update the .env.example, I need to manually update the env vars in Dokploy with it. Sometimes, I forget, which leads to issues. Also, it's good for self-documentation; you may add an env var with a default and never override it, and after time you may forget about it, having this feature also prevents this.

Describe the solution you'd like

In the environment variables tab, add a sub tab named something like "example", and fill it with the .env.example you find in the root dir of the downloaded project.

Describe alternatives you've considered

I don't see one. It should be manually handled by the user otherwise.

Additional context

No response

Will you send a PR to implement it?

No

Start in the environment variables tab and trace how the downloaded project's root directory is accessed. Use the requested .env.example location and the proposed example subtab as the scope; done means the tab displays the discovered example environment variables for the project.