Add ability to remove Games that are removed from GOG Account from Manifest

[Kalanyr]

GOG removed Sunless_Sea_Zubmariner and merged it into Sunless Sea as DLC , gogrepo can't handle this.
This adds that facility, if an update by ID is done (number or name) and not found on GOG but is in the manifst, it deletes the manifest entry. Likewise if a full update (not skipknown or update) is done, it will remove any games from the manifest that are no longer present on the GOG account.

This isn't just a convenience feature either, the old items being in the manifest means that clean doesn't remove the files, and download will try and download them from locations on GOG that never exist, which results in errors.

[eddie3]

Thanks for the PR Kalanyr. This is something I've been meaning to get around to fixing. I hope to review your PR and test it this week, along with the other PRs.

[coughlanio]

Multiple iterations over the same data, can be handled in one for loop.

[HamsterExAstris]

Are the following errors what you were seeing? (Don't want to spend time chasing this down if you already have a fix. :))

13:42:56 | (1 / 1) fetching game details for wasteland_2_directors_cut...
13:43:20 | request failed: HTTP Error 404: Not Found. will not retry.
13:43:20 | failed to fetch https://www.gog.com/downlink/file/wasteland_2_directors_cut_digital_deluxe_edition_upgrade/34743

13:44:04 | (1 / 1) fetching game details for wasteland_2_kickstarter...
13:44:40 | request failed: HTTP Error 404: Not Found. will not retry.
13:44:40 | failed to fetch https://www.gog.com/downlink/file/wasteland_2_directors_cut_digital_deluxe_edition_upgrade/34743