feat: Add samples for Metadata context list, get, and create#1525

SinaChavoshi merged 18 commits into

googleapis:maingoogleapis/python-aiplatform:mainfrom

SinaChavoshi:sdk_samples_list_get_create_for_contextSinaChavoshi/python-aiplatform:sdk_samples_list_get_create_for_contextCopy head branch name to clipboard