zsh/prezto: add package option (#5938)

Allow setting a custom package for `programs.zsh.prezto`.

modules/programs/zsh.nix

@@ -671,7 +671,7 @@ in
 
         ''
         ${optionalString cfg.prezto.enable
-            (builtins.readFile "${pkgs.zsh-prezto}/share/zsh-prezto/runcoms/zshrc")}
+            (builtins.readFile "${cfg.prezto.package}/share/zsh-prezto/runcoms/zshrc")}
 
         ${concatStrings (map (plugin: ''
           if [[ -f "$HOME/${pluginsDir}/${plugin.name}/${plugin.file}" ]]; then

modules/programs/zsh/prezto.nix

@@ -14,6 +14,8 @@ let
     options = {
       enable = mkEnableOption "prezto";
 
+      package = mkPackageOption pkgs "prezto" { default = "zsh-prezto"; };
+
       caseSensitive = mkOption {
         type = types.nullOr types.bool;
         # See <https://github.com/nix-community/home-manager/issues/2255>.
@@ -379,15 +381,15 @@ in {
   };
   config = mkIf cfg.enable (mkMerge [{
     home.file."${relToDotDir ".zprofile"}".text =
-      builtins.readFile "${pkgs.zsh-prezto}/share/zsh-prezto/runcoms/zprofile";
+      builtins.readFile "${cfg.package}/share/zsh-prezto/runcoms/zprofile";
     home.file."${relToDotDir ".zlogin"}".text =
-      builtins.readFile "${pkgs.zsh-prezto}/share/zsh-prezto/runcoms/zlogin";
+      builtins.readFile "${cfg.package}/share/zsh-prezto/runcoms/zlogin";
     home.file."${relToDotDir ".zlogout"}".text =
-      builtins.readFile "${pkgs.zsh-prezto}/share/zsh-prezto/runcoms/zlogout";
-    home.packages = with pkgs; [ zsh-prezto ];
+      builtins.readFile "${cfg.package}/share/zsh-prezto/runcoms/zlogout";
+    home.packages = [ cfg.package ];
 
     home.file."${relToDotDir ".zshenv"}".text =
-      builtins.readFile "${pkgs.zsh-prezto}/share/zsh-prezto/runcoms/zshenv";
+      builtins.readFile "${cfg.package}/share/zsh-prezto/runcoms/zshenv";
     home.file."${relToDotDir ".zpreztorc"}".text = ''
       # Generated by Nix
       ${optionalString (cfg.caseSensitive != null) ''