Loosely related to #7618 and #2082

While this isn't required to package lighthouse for Gentoo, providing a tarball of all of your dependencies would make the whole process cleaner. This is also a prerequisite for building packages on, for example, launchpad or the OpenSUSE Build Service.

This would look something like adding the following to your Release Suite workflow:

cargo vendor
XZ_OPT='-T0 -9' tar -acf vendor.tar.xz vendor

Then signing and uploading it the same way your do your binary tarballs.

See also: https://wiki.gentoo.org/wiki/Writing_Rust_ebuilds#Using_a_vendor_tarball_like_in_Go_ebuilds