avldrums-lv2: alias to x42-avldrums

[orivej]

Motivation for this change

x42 stuff has two names, sometimes distantly related (x42-autotune is aka fat1.lv2). It seems that x42 names are better because they are more recognizable (as belonging to x42-plugins.com), they are used in URLs (https://x42-plugins.com/x42/x42-avldrums) and as the names of packages (https://x42-plugins.com/x42/linux/).

Fixes #83649

cc @magnetophon

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• 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 nixpkgs-review --run "nixpkgs-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)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[magnetophon]

LGTM!