[Housekeeping] Store the upload event as a datetime rather than a date (#269)

* [WIP] renamed and migrated upload_date column

* Refactored yt-dlp media module

* Refactored parse_upload_date

* Refactored media item upload_date_index

* Got media tests running

* Refactored media item table live

* Cleaned up the stragglers

* Fixed old oversight re: original_url

test/support/files/media_metadata.json

@@ -9637,7 +9637,7 @@
   "uploader_url": "https://www.youtube.com/@PinchflatTestChannel",
   "upload_date": "20210720",
   "availability": "public",
-  "original_url": "ABC123",
+  "original_url": "https://www.youtube.com/watch?v=ABC123",
   "webpage_url_basename": "watch",
   "webpage_url_domain": "youtube.com",
   "extractor": "youtube",