Missing comic book mimetype icons

### Problem

Mimetype icons are missing for `.cbz` and `.cbr` files, mimetypes `application/vnd.comicbook+cbz` and `application/vnd.comicbook-cbr`.

These are zip and rar archive files with images inside. They can be read by almost any ebook or pdf reader (Evince, Okular, Calibre, etc). Right now they just default to the document icon.

### Proposal

Possible solutions:

1) Symlink to archive icon
2) Symlink to ebook icon
3) Make a new unique icon

They are archive files but, like epub/ebook, they are books within an archive file so 2 might make a little more sense since they are technically electronic books. If 3, I don't know if I could make an icon that meets the standards for this theme but I could try if 1 and 2 aren't good solutions. Maybe the ebook icon with a speech bubble or something would be simple enough.

### Prior Art (Optional)

_No response_

Review the existing archive and ebook mimetype icon entries in the icon theme to compare their naming and available targets. Decide whether the .cbz and .cbr mimetypes should use archive, ebook, or new icons, then ensure both application/vnd.comicbook+cbz and application/vnd.comicbook-cbr no longer fall back to the document icon.

Written by the indexing model from the issue text.