Update EMSDK to 5.0.0 (#479)

Emscripten 4.0.12 introduced breaking change by changing module factory
to always return promise even if `WASM_ASYNC_COMPILATION=0`. To overcome this, build emscripten compiler without MODULARIZE with custom export of `createRevive`.

js/emscripten/embed/extern-post.js

@@ -0,0 +1,6 @@
+return Module;
+}
+if (typeof module === "object" && typeof module.exports === "object") {
+  module.exports = createRevive;
+} else if (typeof define === "function" && define["amd"])
+  define([], () => createRevive);