build: add GN configurations for simdjson

PR-URL: https://github.com/nodejs/node/pull/50831
Reviewed-By: Keyhan Vakil <kvakil@sylph.kvakil.me>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>

unofficial.gni

@@ -159,6 +159,7 @@ template("node_gn_build") {
       "deps/nghttp2",
       "deps/ngtcp2",
       "deps/postject",
+      "deps/simdjson",
       "deps/simdutf",
       "deps/uvwasi",
       "//third_party/zlib",