feat: ListFunctions now include metadata which indicates whether a function is a GEN_1 or GEN_2 function

PiperOrigin-RevId: 535193873

Source-Link: googleapis/googleapis@d6b7eb5

Source-Link: googleapis/googleapis-gen@822ccd0
Copy-Tag: eyJwIjoiYXBpcy9Hb29nbGUuQ2xvdWQuRnVuY3Rpb25zLlYyLy5Pd2xCb3QueWFtbCIsImgiOiI4MjJjY2QwOWNjMWU5ZjhhNGFiMDEyNWNjOTNlZmZlMjZhYjg4MmMxIn0=

Author: gcf-owl-bot[bot]