refactor: Update GitHub connector to use gitingest CLI

- Refactored GitHubConnector to utilize gitingest CLI via subprocess, improving performance and avoiding async issues with Celery.
- Updated ingestion method to handle repository digests more efficiently, including error handling for subprocess execution.
- Adjusted GitHub indexer to call the new synchronous ingestion method.
- Clarified documentation regarding the optional nature of the Personal Access Token for public repositories.

surfsense_web/components/assistant-ui/connector-popup/config/connector-status-config.json

@@ -24,11 +24,6 @@
 			"enabled": true,
 			"status": "warning",
 			"statusMessage": "Some requests may be blocked if not using Firecrawl."
-		},
-		"GITHUB_CONNECTOR": {
-			"enabled": false,
-			"status": "maintenance",
-			"statusMessage": "Rework in progress."
 		}
 	},
 	"globalSettings": {