treewide: begin restructuring the module tree

modules/plugins/lsp/null-ls/config.nix

@@ -0,0 +1,41 @@
+{
+  config,
+  lib,
+  ...
+}: let
+  inherit (lib.modules) mkIf mkMerge;
+  inherit (lib.attrsets) mapAttrs;
+  inherit (lib.nvim.dag) entryAnywhere entryAfter entryBetween;
+
+  cfg = config.vim.lsp;
+in {
+  config = mkIf cfg.null-ls.enable (mkMerge [
+    {
+      vim = {
+        lsp.enable = true;
+        startPlugins = ["none-ls"];
+
+        luaConfigRC.null_ls-setup = entryAnywhere ''
+          local null_ls = require("null-ls")
+          local null_helpers = require("null-ls.helpers")
+          local null_methods = require("null-ls.methods")
+          local ls_sources = {}
+        '';
+
+        luaConfigRC.null_ls = entryAfter ["null_ls-setup" "lsp-setup"] ''
+          require('null-ls').setup({
+            debug = false,
+            diagnostics_format = "[#{m}] #{s} (#{c})",
+            debounce = 250,
+            default_timeout = 5000,
+            sources = ls_sources,
+            on_attach = default_on_attach
+          })
+        '';
+      };
+    }
+    {
+      vim.luaConfigRC = mapAttrs (_: v: (entryBetween ["null_ls"] ["null_ls-setup"] v)) cfg.null-ls.sources;
+    }
+  ]);
+}

modules/plugins/lsp/null-ls/default.nix

@@ -0,0 +1,6 @@
+{
+  imports = [
+    ./config.nix
+    ./null-ls.nix
+  ];
+}

modules/plugins/lsp/null-ls/null-ls.nix

@@ -0,0 +1,14 @@
+{lib, ...}: let
+  inherit (lib.options) mkEnableOption mkOption;
+  inherit (lib.types) attrsOf str;
+in {
+  options.vim.lsp.null-ls = {
+    enable = mkEnableOption "null-ls, also enabled automatically";
+
+    sources = mkOption {
+      description = "null-ls sources";
+      type = attrsOf str;
+      default = {};
+    };
+  };
+}