plugins/lsp: add vls language server

plugins/lsp/language-servers/vls.nix

@@ -0,0 +1,28 @@
+{
+  lib,
+  config,
+  ...
+}:
+with lib; let
+  cfg = config.plugins.lsp.servers.vls;
+in {
+  options.plugins.lsp.servers.vls = {
+    autoSetFiletype = mkOption {
+      type = types.bool;
+      description = ''
+        Files with the `.v` extension are not automatically detected as vlang files.
+        If this option is enabled, Nixvim will automatically set  the filetype accordingly.
+      '';
+      default = true;
+      example = false;
+    };
+  };
+
+  config =
+    mkIf cfg.enable
+    {
+      filetype.extension =
+        mkIf cfg.autoSetFiletype
+        {v = "vlang";};
+    };
+}