Issue: Content filter for external content not working #616

Describe the bug
Around #602, the filtering of the external post types stopped working. Post types with ../ in their path won't appear.

Sample config:

{
  "$schema": "https://frontmatter.codes/config/content.pagefolders.schema.json",
  "title": "Components",
  "path": "[[workspace]]/../hugo-modules/documentation",
  "contentTypes": ["component"]
}

To Reproduce
Steps to reproduce the behavior:

1. Clone kollitsch.dev, hugo-modules, and hugo-theme into the same folder next to each other
2. Load the workspace via kollitsch.dev/kollitsch-dev.workspace
3. Check the Frontmatter Dashboard
4. set "Showing" filter to anything other than "components" < the posts group is loaded
5. set "Showing" filter to "components" < the last selection stays visible

Desktop (please complete the following information):

• OS: Ubuntu 22.04 LTS
• Browser Chrome latest
• VSCode and Plugin are on the latest versions (not preview or beta)