feat(runtime): Add example for extension with ops (#19204)

Spend quite some time trying to get this working. With proper example
would have been a lot faster. So this is pr with the example. I also
rearranged examples a little bit to allow for addition of more examples

runtime/examples/extension_with_esm/bootstrap.js

@@ -0,0 +1,5 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+function hello() {
+  console.log("Hello from extension!");
+}
+globalThis.Extension = { hello };

runtime/examples/extension_with_esm/main.js

@@ -0,0 +1,4 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+console.log("Hello world!");
+console.log(Deno);
+Extension.hello();

runtime/examples/extension_with_esm/main.rs

@@ -0,0 +1,36 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+use std::path::Path;
+use std::rc::Rc;
+
+use deno_core::error::AnyError;
+use deno_core::FsModuleLoader;
+use deno_core::ModuleSpecifier;
+use deno_runtime::permissions::PermissionsContainer;
+use deno_runtime::worker::MainWorker;
+use deno_runtime::worker::WorkerOptions;
+
+deno_core::extension!(
+  hello_runtime,
+  esm_entry_point = "ext:hello_runtime/bootstrap.js",
+  esm = ["bootstrap.js"]
+);
+
+#[tokio::main]
+async fn main() -> Result<(), AnyError> {
+  let js_path = Path::new(env!("CARGO_MANIFEST_DIR"))
+    .join("examples/extension_with_esm/main.js");
+  let main_module = ModuleSpecifier::from_file_path(js_path).unwrap();
+  let mut worker = MainWorker::bootstrap_from_options(
+    main_module.clone(),
+    PermissionsContainer::allow_all(),
+    WorkerOptions {
+      module_loader: Rc::new(FsModuleLoader),
+      extensions: vec![hello_runtime::init_ops_and_esm()],
+      ..Default::default()
+    },
+  );
+  worker.execute_main_module(&main_module).await?;
+  worker.run_event_loop(false).await?;
+  Ok(())
+}