Scrape only missing resources, not entire files

[jmt-gh]

Describe the feature / request
Currently, if I have a full set of media scraped, except for videos, and I want to scrape videos, Skyscraper will refresh the entire cache, and re-scrape everything I've already got. Ideally, Skyscraper could understand / have the ability to only scrape missing resources (currently the documentation only shows how to scrape entire files based on missing resources, not the individual resources themselves)

Additional context
This would save unnecessary hammering on screenscraper.fr, spurious API calls, and bandwidth

[jmt-gh]

I figured out a way to do this in case anyone else ever runs in to this:

1. do your scraping, generate your media, etc. etc.
2. decide you want to scrape a new resource, like video
3. in your config, set cacheCovers, cacheScreenshots, etc. to false
4. in your config, set whatever you resource you want to true (e.g videos)
5. run the scraper with --refresh. it should only be fetching videos (you can tell by the API requests remaining going down by 1 each game now, instead of 4 or 5 if you had everything enabled)
6. generate your media / gamelist
7. your media folder and gamelist should now have everything in it!

[jmt-gh]

This does seem to require rehashing each file though, which is suboptimal given that the cache already has the hashes in quickid?