feat: enable Gitea auto-start

- The Gitea installer now automatically starts the Gitea server after installation.
- Updated the installer to include a `start()` function.
- Added PostgreSQL installation and configuration to the Gitea installer.
- Improved error handling and logging.
- Updated configuration file template for better clarity and consistency.
- Renamed some variables for better readability.

Co-authored-by: mariobassem12 <mariobassem12@gmail.com>

lib/installers/infra/gitea/gitea_factory_.v

@@ -170,7 +170,7 @@ pub fn (mut self GiteaServer) start() ! {
 		}
 		time.sleep(100 * time.millisecond)
 	}
-	return error('gitea did not install properly.')
+	return error('cannot start gitea')
 }
 
 pub fn (mut self GiteaServer) install_start(args InstallArgs) ! {