Function create_anim_spritesheet_frame_configs

Create list of animation frame config, can be used directly as part of anim_config's frames parameter.

This function will generate list of frame configs based on the spritesheet_config attached to the associated spritesheet. This function requires that the given key is a spritesheet key i.e. a key associated with loaded spritesheet, loaded in using load_spritesheet function.

Will return empty frame configs if key is not associated with a spritesheet.