feat: apply new module format to lsp plugins

modules/lsp/lsp-signature/config.nix

@@ -0,0 +1,21 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}:
+with lib;
+with builtins; let
+  cfg = config.vim.lsp;
+in {
+  config = mkIf (cfg.enable && cfg.lspSignature.enable) {
+    vim.startPlugins = [
+      "lsp-signature"
+    ];
+
+    vim.luaConfigRC.lsp-signature = nvim.dag.entryAnywhere ''
+      -- Enable lsp signature viewer
+      require("lsp_signature").setup()
+    '';
+  };
+}

modules/lsp/lsp-signature/default.nix

@@ -0,0 +1,6 @@
+_: {
+  imports = [
+    ./lsp-signature.nix
+    ./config.nix
+  ];
+}

modules/lsp/lsp-signature/lsp-signature.nix

@@ -0,0 +1,16 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}:
+with lib;
+with builtins; let
+  cfg = config.vim.lsp;
+in {
+  options.vim.lsp = {
+    lspSignature = {
+      enable = mkEnableOption "lsp signature viewer";
+    };
+  };
+}