Repo was only used in two locations:
1. StripeButtons.set for `isCommons` - can be replaced by `descriptionUrl.includes('//commons.wikimedia.org/')`
2. EmbedFileFormatter.getSiteLink (unused)
Furthermore:
- Simplify StripeButtons (we only have one button)
- Unwrap info objects consisting of `ImageModel` and `Repo`
- Remove unused EmbedFileFormatter.getSiteLink
- Inline EmbedFileFormatter.getCaption and EmbedFileFormatter.getLinkUrl
- Fix JSDoc type `ImageModel`
Reduces mmv bundle size from 28012 to 27246.
Bug: T77349
Change-Id: Ia4388fe4d5e1d6112a992e826453cd5799a6a4b4
