modules: start breaking down core modules; simplify tree structure

modules/plugins/lsp/lsp-signature/config.nix

@@ -0,0 +1,27 @@
+{
+  config,
+  lib,
+  ...
+}: let
+  inherit (lib) mkIf nvim optionalString;
+
+  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({
+        ${optionalString (config.vim.ui.borders.plugins.lsp-signature.enable) ''
+        bind = true, -- This is mandatory, otherwise border config won't get registered.
+        handler_opts = {
+          border = "${config.vim.ui.borders.plugins.lsp-signature.style}"
+        }
+      ''}
+      })
+    '';
+  };
+}

modules/plugins/lsp/lsp-signature/default.nix

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

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

@@ -0,0 +1,13 @@
+{
+  config,
+  lib,
+  ...
+}: let
+  inherit (lib) mkEnableOption;
+in {
+  options.vim.lsp = {
+    lspSignature = {
+      enable = mkEnableOption "lsp signature viewer";
+    };
+  };
+}