style tables and add out/err highlights

improve projector open error message if an invalid monitor index is passed.
it now prints the monitor name and suggests `gobs-cli prj ls-m`

improve error message for sceneitem commands if a scene item in a group is queried without the --group flag.

screenshot.go

@@ -36,6 +36,6 @@ func (cmd *ScreenshotSaveCmd) Run(ctx *context) error {
 		return fmt.Errorf("failed to take screenshot: %w", err)
 	}
 
-	fmt.Fprintf(ctx.Out, "Screenshot saved to %s.\n", cmd.FilePath)
+	fmt.Fprintf(ctx.Out, "Screenshot saved to %s.\n", ctx.Style.Highlight(cmd.FilePath))
 	return nil
 }