`jellyfin` appeared unsupported on `aarch64` due to `dotnet` platform
support in nixpkgs, but there are ARM64 downloads of the `dotnet` SDKs
available. This change follows the kind of pattern used in the
`firecracker` packaging to support selective x86_64/arm64 downloads.

With this change I can build `jellyfin` on a Raspberry Pi 4. The other
content hashes have been filled in, and all build successfully, but
they have not been further tested.

Until recently, libusb-compat propagated libusb1 and many packages unknowingly used it to obtain libusb1.
When NixOS/nixpkgs#82944 removed this evil propagation, it broke many packages with such incorrect assumption.
This patch trades the breakage of packages wanting libusb1 caused by the PR for a hopefully less common breakage of the packages relying on the compat library.

https://chromereleases.googleblog.com/2020/04/stable-channel-update-for-desktop_27.html

This update includes 2 security fixes.

CVEs: CVE-2020-6462 CVE-2020-6461

fish-shell/fish-shell@3.1.1...3.1.2

"This release of fish fixes a major issue discovered in fish 3.1.1:
Commands such as `fzf` and `enhancd`, when used with `eval`, would hang.
`eval` buffered output too aggressively, which has been fixed."

fish: 3.1.1 -> 3.1.2

chromium: 81.0.4044.122 -> 81.0.4044.129