Add `runtime_assets` property to `filters` resource

[majormoses]

Pull Request Checklist

closes #64 @webframp I took a quick look and I did not see any tests for filters, am I missing something or did they not get done. I can take a closer look over the weekend possibly. I also need to actually look more closely at the docs since it was not clear to me what

General

• [ ] Update Changelog following the conventions laid out here

• [ ] Update README with any necessary configuration snippets

• [ ] Cookstyle (rubocop) passes

• [ ] Foodcritic passes

• [ ] Rspec (unit tests) passes

• [ ] Inspec (integration tests) passes

New Features

• [ ] Added a Testing Artifact as either an automated test or a manual artifact on the PR.

• [ ] Adedd documentation for it to the README.md

Purpose

Add support for runttime_assets on filters.

API Docs: https://docs.sensu.io/sensu-go/5.13/api/filters/

Known Compatibility Issues

none

[webframp]

@majormoses Looks good, seems like they were just missed. They only existed on the check resource so far from what I can tell.