When able to be parsed, store the created date for a video file from meta,
since this is useful separately from the dates on the file itself.
Introduces `wp_get_media_creation_timestamp()` to read the timestamp from
getID3 and a `wp_read_video_metadata` filter analogous to
`wp_read_image_metadata`.
Fixes#35218.
Props stevegrunwell, joemcgill, desrosj, blobfolio, mikeschroder.
git-svn-id: https://develop.svn.wordpress.org/trunk@41746 602fd350-edb4-49c9-b593-d223f7449a82
Mike Schroder