Create common functions parse_date, parse_month_year_date and parse_datetime.
Those functions support trying multiple formats, and come with default formats lists that support most of the date format encountered so far.
Notable change: year-month dates are now set to the end of month (impacted couchbase-server and ibm-aix).
Fetch Looker versions with their dates from the Google Cloud release notes RSS feed: https://cloud.google.com/feeds/looker-release-notes.xml.
Only version above 23.0 are retrieved, as prior version were not announced in the Google Cloud release notes.