plugins/treesitter-rainbow: add plugin + test

plugins/languages/treesitter/treesitter-rainbow.nix

@@ -0,0 +1,66 @@
+{
+  pkgs,
+  lib,
+  config,
+  ...
+}:
+with lib; let
+  helpers = import ../../helpers.nix {inherit lib;};
+in {
+  options.plugins.treesitter-rainbow =
+    helpers.extraOptionsOptions
+    // {
+      enable = mkEnableOption "treesitter-rainbow";
+
+      package = helpers.mkPackageOption "treesitter-rainbow" pkgs.vimPlugins.nvim-ts-rainbow2;
+
+      disable =
+        helpers.defaultNullOpts.mkNullable (types.listOf types.str) "[]"
+        "List of languages you want to disable the plugin for.";
+
+      query =
+        helpers.defaultNullOpts.mkStr "rainbow-parens"
+        "The query to use for finding delimiters.";
+
+      strategy =
+        helpers.defaultNullOpts.mkStr "require('ts-rainbow').strategy.global"
+        "The query to use for finding delimiters. Directly provide lua code.";
+
+      hlgroups =
+        helpers.defaultNullOpts.mkNullable (types.listOf types.str)
+        ''
+          [
+            "TSRainbowRed"
+            "TSRainbowYellow"
+            "TSRainbowBlue"
+            "TSRainbowOrange"
+            "TSRainbowGreen"
+            "TSRainbowViolet"
+            "TSRainbowCyan"
+          ]
+        ''
+        "The list of highlight groups to apply.";
+    };
+
+  config = let
+    cfg = config.plugins.treesitter-rainbow;
+  in
+    mkIf cfg.enable {
+      warnings = mkIf (!config.plugins.treesitter.enable) [
+        "Nixvim: treesitter-rainbow needs treesitter to function as intended"
+      ];
+
+      extraPlugins = [cfg.package];
+
+      plugins.treesitter.moduleConfig.rainbow =
+        {
+          enable = true;
+
+          inherit (cfg) disable;
+          inherit (cfg) query;
+          strategy = helpers.ifNonNull' cfg.strategy (helpers.mkRaw cfg.strategy);
+          inherit (cfg) hlgroups;
+        }
+        // cfg.extraOptions;
+    };
+}