modules: start breaking down core modules; simplify tree structure

modules/plugins/lsp/default.nix

@@ -0,0 +1,21 @@
+_: {
+  imports = [
+    # nvim lsp support
+    ./config.nix
+    ./module.nix
+
+    ./lspconfig
+    ./lspsaga
+    ./null-ls
+
+    # lsp plugins
+    ./lspsaga
+    ./nvim-code-action-menu
+    ./trouble
+    ./lsp-signature
+    ./lightbulb
+    ./lspkind
+    ./lsplines
+    ./nvim-docs-view
+  ];
+}