vimPlugins: make usage of luaPackages less confusing

right now the src is ignored in:

```
lush-nvim = buildNeovimPlugin {
pname = "lush.nvim";
version = "2022-08-09";
src = fetchFromGitHub {
owner = "rktjmp";
repo = "lush.nvim";
rev = "6b9f399245de7bea8dac2c3bf91096ffdedfcbb7";
sha256 = "0rb77rwmbm438bmbjfk5hwrrcn5sihsa1413bdpc27rw3rrn8v8z";
};
meta.homepage = "https://github.com/rktjmp/lush.nvim/";
};
```

which is very confusing. With this PR, we correctly override the src and
the version of the package. We introduce a rockspecVersion attribute of
lua package to be able to still find the rockspec when the
"version" field needs to be different than "rockspecVersion".

pkgs/applications/editors/neovim/build-neovim-plugin.nix

···
 { lib
 , stdenv
-, buildVimPluginFrom2Nix
-, buildLuarocksPackage
-, lua51Packages
+, lua
 , toVimPlugin
 }:
 let
···
     , ...
   }@attrs:
     let
-      originalLuaDrv = lua51Packages.${luaAttr};
-      luaDrv = lua51Packages.luaLib.overrideLuarocks originalLuaDrv (drv: {
+      originalLuaDrv = lua.pkgs.${luaAttr};
+
+      luaDrv = (lua.pkgs.luaLib.overrideLuarocks originalLuaDrv (drv: {
         extraConfig = ''
           -- to create a flat hierarchy
           lua_modules_path = "lua"
         '';
+        })).overrideAttrs (drv: {
+        version = attrs.version;
+        rockspecVersion = drv.rockspecVersion;
       });
-      finalDrv = toVimPlugin (luaDrv.overrideAttrs(oa: {
+
+      finalDrv = toVimPlugin (luaDrv.overrideAttrs(oa: attrs // {
           nativeBuildInputs = oa.nativeBuildInputs or [] ++ [
-            lua51Packages.luarocksMoveDataFolder
+            lua.pkgs.luarocksMoveDataFolder
           ];
         }));
     in

pkgs/applications/editors/neovim/utils.nix

···
 { lib
-, buildLuarocksPackage
 , callPackage
 , vimUtils
 , nodejs
 , neovim-unwrapped
 , bundlerEnv
 , ruby
+, lua
 , python3Packages
 , writeText
 , wrapNeovimUnstable
···
   inherit legacyWrapper;
 
   buildNeovimPluginFrom2Nix = callPackage ./build-neovim-plugin.nix {
-    inherit (vimUtils) buildVimPluginFrom2Nix toVimPlugin;
-    inherit buildLuarocksPackage;
+    inherit (vimUtils) toVimPlugin;
+    inherit lua;
   };
 }

pkgs/development/interpreters/lua-5/build-lua-package.nix

···
 , luaLib
 }:
 
-{
-pname
+{ pname
 , version
+# we need rockspecVersion to find the .rockspec even when version changes
+, rockspecVersion ? version
 
 # by default prefix `name` e.g. "lua5.2-${name}"
 , namePrefix ? "${lua.pname}${lua.sourceVersion.major}.${lua.sourceVersion.minor}-"
···
 # Keep extra attributes from `attrs`, e.g., `patchPhase', etc.
 
 let
-  generatedRockspecFilename = "${rockspecDir}/${pname}-${version}.rockspec";
+  generatedRockspecFilename = "${rockspecDir}/${pname}-${rockspecVersion}.rockspec";
 
   # TODO fix warnings "Couldn't load rockspec for ..." during manifest
   # construction -- from initial investigation, appears it will require
···
   # luarocks only looks for rockspecs in the default/system tree instead of all
   # configured trees)
   luarocks_config = "luarocks-config.lua";
-  luarocks_content = let
-    generatedConfig = luaLib.generateLuarocksConfig {
-      externalDeps = externalDeps ++ externalDepsGenerated;
-      inherit extraVariables;
-      inherit rocksSubdir;
-      inherit requiredLuaRocks;
-    };
-    in
-      ''
-      ${generatedConfig}
-      ${extraConfig}
-      '';
-
-  rocksSubdir = "${attrs.pname}-${version}-rocks";
 
   # Filter out the lua derivation itself from the Lua module dependency
   # closure, as it doesn't have a rock tree :)
···
     );
   externalDeps' = lib.filter (dep: !lib.isDerivation dep) externalDeps;
 
-  luarocksDrv = luaLib.toLuaModule ( lua.stdenv.mkDerivation (
-builtins.removeAttrs attrs ["disabled" "checkInputs" "externalDeps" "extraVariables"] // {
+  luarocksDrv = luaLib.toLuaModule ( lua.stdenv.mkDerivation (self: let
+
+    rocksSubdir = "${self.pname}-${self.version}-rocks";
+    luarocks_content = let
+      generatedConfig = luaLib.generateLuarocksConfig {
+        externalDeps = externalDeps ++ externalDepsGenerated;
+        inherit extraVariables rocksSubdir requiredLuaRocks;
+      };
+      in
+        ''
+        ${generatedConfig}
+        ${extraConfig}
+        '';
+    in builtins.removeAttrs attrs ["disabled" "externalDeps" "extraVariables"] // {
 
-  name = namePrefix + pname + "-" + version;
+  name = namePrefix + pname + "-" + self.version;
+  inherit rockspecVersion;
 
   nativeBuildInputs = [
     wrapLua
     luarocks
-  ] ++ lib.optionals doCheck ([ luarocksCheckHook ] ++ checkInputs);
+  ] ++ lib.optionals doCheck ([ luarocksCheckHook ] ++ self.checkInputs);
 
   buildInputs = buildInputs
     ++ (map (d: d.dep) externalDeps');

pkgs/development/interpreters/lua-5/hooks/luarocks-move-data.sh

···
 luarocksMoveDataHook () {
     echo "Executing luarocksMoveDataHook"
     if [ -d "$out/$rocksSubdir" ]; then
-        cp -rfv "$out/$rocksSubdir/$pname/$version/." "$out"
+        cp -rfv "$out/$rocksSubdir/$pname/$rockspecVersion/." "$out"
     fi
 
     echo "Finished executing luarocksMoveDataHook"

pkgs/top-level/all-packages.nix

···
   };
 
   neovimUtils = callPackage ../applications/editors/neovim/utils.nix {
-    inherit (lua51Packages) buildLuarocksPackage;
+    lua = lua5_1;
   };
   neovim = wrapNeovim neovim-unwrapped { };