Rust: Report bundled library in the spec files

+++ This bug was initially created as a clone of Bug #1989546 +++

This is a Rust project, which bundles several Rust libraries, currently not reported in the spec file.

There are Fedora guides:
+ https://docs.fedoraproject.org/en-US/packaging-guidelines/Rust/
+ https://fedoraproject.org/wiki/Bundled_Libraries?rd=Packaging:Bundled_Libraries
+ https://docs.fedoraproject.org/en-US/packaging-guidelines/#bundling

=> The spec file currently does not list the Rust Libraries. I think
there was a discussion to port this Fedora guideline to RHEL, but I am
not aware of the status of this RHEL Rust package guideline.

This would be useful for, among others, product security, so that we can track flaws affecting libraries bundled in project.