zathura-core: 0.4.1 -> 0.4.3, zathura-cb: init at 0.1.8 and refactoring

[oxzi]

Motivation for this change

This PR introduces some changes regarding the zathura document viewer.

• zathura-core was updated to 0.4.3
• zathura-cb was added at version 0.1.8 to add comic book support
• zathura-pdf-mupdf's src was changed back to zathura's official URL

Each change is in its own commit.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.

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[veprbl]

@GrahamcOfBorg build zathura

[veprbl]

First two changes are duplicate of #57291

[oxzi]

Funny to see two PRs for an older update within one hour. Seems like I was kind of too late.
Thanks for having a look at my proposed changes.