fix(node): add ppid getter for node:process (#22167)

This commit adds `ppid` getter for `node:process` to improve Node
compatibility one step further.

There is one problem though, which is that `Deno.ppid`, which
`process.ppid` internally calls, is actually of type `bigint` although
it's supposed to be `number`. I filed an issue for this (#22166). For
the time being, explciit type conversion from `bigint` to `number` is
applied to match the Node.js behavior.

cli/tests/unit_node/process_test.ts

@@ -121,6 +121,14 @@ Deno.test({
   },
 });
 
+Deno.test({
+  name: "process.ppid",
+  fn() {
+    assertEquals(typeof process.ppid, "number");
+    assertEquals(process.ppid, Deno.ppid);
+  },
+});
+
 Deno.test({
   name: "process.on",
   async fn() {

ext/node/polyfills/process.ts

@@ -558,6 +558,11 @@ class Process extends EventEmitter {
     return pid;
   }
 
+  /** https://nodejs.org/api/process.html#processppid */
+  get ppid() {
+    return Deno.ppid;
+  }
+
   /** https://nodejs.org/api/process.html#process_process_platform */
   get platform() {
     if (!platform) {