yara-x: new package

[egibs]

This PR adds a new package for yara-x which is a replacement for Yara written in Rust. We plan on leveraging this for malcontent at some point, but its general availability would be nice since it takes a while to build and install locally.

Pre-review Checklist

make package/yara-x runs successfully
make test/yara-x runs successfully

For new package PRs only

• This PR is marked as fixing a pre-existing package request bug
  • Alternatively, the PR is marked as related to a pre-existing package request bug, such as a dependency
• REQUIRED - The package is available under an OSI-approved or FSF-approved license
• REQUIRED - The version of the package is still receiving security updates
• This PR links to the upstream project's support policy (e.g. endoflife.date)