Fixes#98769.
Important changes from https://gstreamer.freedesktop.org/releases/1.18/:
* `gst-validate` was renamed to `gst-devtools` upstream:
> * the `gst-validate` tarball has been superseded by
> the `gst-devtools` tarball for consistency with the git module name.
* `gst-python` is now Python 3 only:
> * Python 2.x is no longer supported
Changes the default fetcher in the Rust Platform to be the newer
`fetchCargoTarball`, and changes every application using the current default to
instead opt out.
This commit does not change any hashes or cause any rebuilds. Once integrated,
we will start deleting the opt-outs and recomputing hashes.
See #79975 for details.
A recent upgrade of cargo-vendor changed its output slightly, which
broke all cargoSha256 hashes in nixpkgs.
See https://github.com/NixOS/nixpkgs/issues/60668 for more information.
Since then, a few hashes have been fixed in master by hand, but there
were a lot still to do, so I did all of the ones left over with some
scripts I wrote.
The one hash I wasn’t able to update was habitat's, because it’s
currently broken and the build doesn’t get far enough to produce a
hash anyway.
