modules/performance/combine-plugins: propagate lua dependencies

Plugins from luarocks (e.g. telescope-nvim) have dependencies specified
in propagatedBuildInputs. These dependencies are not added as plugins in
Nvim runtime. They are added to LUA_PATH env var for wrapped neovim.
This commit collects all propagatedBuildInputs from input plugin list
and puts them in the combined plugin.
Note that such dependencies are never combined, because they are not
plugins.

tests/test-sources/modules/performance/combine-plugins.nix

@@ -69,6 +69,17 @@ let
   pluginWithPyDeps3 = mkPlugin "plugin-with-py-deps-3" {
     passthru.python3Dependencies = ps: [ ps.requests ];
   };
+  # Plugins with Lua dependencies
+  ensureDep =
+    drv: dep:
+    drv.overrideAttrs (prev: {
+      propagatedBuildInputs = lib.unique (
+        prev.propagatedBuildInputs or [ ] ++ [ prev.passthru.lua.pkgs.${dep} ]
+      );
+    });
+  pluginWithLuaDeps1 = ensureDep pkgs.vimPlugins.telescope-nvim "plenary-nvim";
+  pluginWithLuaDeps2 = ensureDep pkgs.vimPlugins.nvim-cmp "plenary-nvim";
+  pluginWithLuaDeps3 = ensureDep pkgs.vimPlugins.gitsigns-nvim "nui-nvim";
 in
 {
   # Test basic functionality
@@ -222,6 +233,35 @@ in
       ];
     };
 
+  # Test that plugin lua dependencies are handled
+  lua-dependencies =
+    { config, ... }:
+    {
+      performance.combinePlugins.enable = true;
+      extraPlugins = [
+        simplePlugin1
+        # Duplicated plenary-nvim dependency
+        pluginWithLuaDeps1
+        pluginWithLuaDeps2
+        # nui-nvim dependency
+        pluginWithLuaDeps3
+      ];
+      extraConfigLuaPost = ''
+        -- All packages and its dependencies are importable
+        require("telescope")
+        require("plenary")
+        require("cmp")
+        require("gitsigns")
+        require("nui.popup")
+      '';
+      assertions = [
+        {
+          assertion = pluginCount config.build.nvimPackage config.build.extraFiles "start" == 1;
+          message = "More than one plugin is defined in packpathDirs.";
+        }
+      ];
+    };
+
   # Test that optional plugins are handled
   optional-plugins =
     { config, ... }: