[Knowledge] Folder icons in resource table

## Severity

P3 - Medium (Minor functionality affected)

## Folder icon
- Change the `Folder Open` icon to `Folder` icon
- It's misleading and not consistent to have a `folder open` icon when the accordion is closed, and adds cognitive load since the icon doesn't always match the experience.
- [Link to icons](https://github.com/microsoft/fluentui-system-icons/blob/main/icons_regular.md)

## Folder icon color
- Change the folder color from orange to `Neutral/Foreground/1/Rest`
- The color orange indicates a warning, not something we want to convey in a working state.
- [Link to color tokens](https://storybooks.fluentui.dev/react/?path=/docs/theme-colors--docs)

## Screenshot of experience