vimPlugins.rocks-nvim: add initLua for a working out of the box exper… (#375083)

vimPlugins.rocks-nvim: add initLua for a working out of the box experience

added a test as well. Using NVIM_APPNAME to run "neovim.tests.nvim_with_rocks_nvim" in a minimal sandbox.

pkgs/applications/editors/neovim/tests/default.nix

···
       ${pkgs.perl}/bin/perl -pe "s|\Q$NIX_STORE\E/[a-z0-9]{32}-|$NIX_STORE/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-|g" < "$luarc" > "$luarcGeneric"
     '' + buildCommand);
 
+  nvim_with_rocks_nvim = (
+    wrapNeovimUnstable neovim-unwrapped {
+      extraName = "with-rocks-nvim";
+      wrapperArgs = "--set NVIM_APPNAME test-rocks-nvim";
+      plugins = [ vimPlugins.rocks-nvim ];
+    }
+  );
 in
   pkgs.recurseIntoAttrs (rec {
 
···
   can_require_transitive_deps =
     runTest nvim-with-luasnip ''
     ${nvim-with-luasnip}/bin/nvim -i NONE --cmd "lua require'jsregexp'" -e +quitall!
+  '';
+
+  inherit nvim_with_rocks_nvim;
+  rocks_install_plenary = runTest nvim_with_rocks_nvim ''
+    ${nvim_with_rocks_nvim}/bin/nvim -V3log.txt -i NONE +'Rocks install plenary.nvim' +quit! -e
   '';
 
   inherit (vimPlugins) corePlugins;

pkgs/applications/editors/vim/plugins/overrides.nix

···
       "papis-nvim"
       "rest-nvim"
       "rocks-config-nvim"
-      "rocks-nvim"
       "rtp-nvim"
       "telescope-manix"
       "telescope-nvim"
···
   in
   lib.genAttrs luarocksPackageNames toVimPackage
 )
+// {
+
+  rocks-nvim =
+    (neovimUtils.buildNeovimPlugin {
+      luaAttr = luaPackages.rocks-nvim;
+    }).overrideAttrs
+      (oa: {
+        passthru = oa.passthru // {
+          initLua = ''
+            vim.g.rocks_nvim = {
+              luarocks_binary = "${neovim-unwrapped.lua.pkgs.luarocks_bootstrap}/bin/luarocks"
+              }
+          '';
+        };
+
+      });
+}