Add download support to CLI and client

Implemented file and folder download functionality in the CLI and GofileClient, including new CLI arguments for downloading by URL or content ID and specifying output directory.

test_upload.py

@@ -0,0 +1,7 @@
+from gofilepy import GofileClient
+
+client = GofileClient()
+# client = GofileClient(token="YOUR_TOKEN_HERE")  # Optional token for private uploads
+file = client.upload(file=open("./test_upload.py", "rb"))
+print(file.name)
+print(file.page_link)  # View and download file at this link