Update ChatCompletionClient

Instead of CreateChatCompletion* accepting a pointer to a slice of reply
messages, it accepts a callback which is called with each successive
reply the conversation.

This gives the caller more flexibility in how it handles replies (e.g.
it can react to them immediately now, instead of waiting for the entire
call to finish)

pkg/cmd/prompt.go

@@ -31,7 +31,7 @@ func PromptCmd(ctx *lmcli.Context) *cobra.Command {
 				},
 			}
 
-			_, err := cmdutil.FetchAndShowCompletion(ctx, messages)
+			_, err := cmdutil.FetchAndShowCompletion(ctx, messages, nil)
 			if err != nil {
 				return fmt.Errorf("Error fetching LLM response: %v", err)
 			}