feat(file-preview-card-group): add class for card description

[LuLaValva]

• This PR contains CSS changes
• This PR does not contain CSS changes

Description

• Add a class for the descriptions of file-preview-card within file-preview-card-group

Screenshots

Checklist

• I verify the build is in a non-broken state
• I verify all changes are within scope of the linked issue

• I regenerated all CSS files under dist folder
• I tested the UI in all supported browsers
• I did a visual regression check of the components impacted by doing a Percy build and approved the build
• I tested the UI in dark mode and RTL mode
• I added/updated/removed Storybook coverage as appropriate

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Latest commit: 36a3988

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[LuLaValva]

After some discussion offline, I ended up doing kind of a major refactor of the way that file-preview-card is organized. The names that changed were taken from the design side, but I'm not super happy with a few of them and would be happy to change. Please take a look.

[ArtBlue]

Looks good overall. A couple of minor comments.

The rest (naming convention) we'll discuss "offline."

[ArtBlue]

Was this spec-ed in ems? Seems like we should be using a token.

[LuLaValva]

It really just needs to be any number larger than the height so edges will be rounded, I used em since that will work even if a chrome extension or something changes font size to be larger.