[TS]: builder, Fix requiredField(). Verity that the field is present in the vtable (#7739) (#7752)

* [TS]: Fix vtable creation for consecutive required fileds (#7739)

* handle feedback

* comment the schema

* comment change in builder.ts

* [TS]: builder, Fix requiredField()

Verifty that the field is present in the vtable.

* restore monsterdata binary file

Co-authored-by: Derek Bailey <derekbailey@google.com>

tests/ts/JavaScriptRequiredStringTest.js

@@ -0,0 +1,32 @@
+import assert from 'assert'
+import * as flatbuffers from 'flatbuffers';
+import { Foo } from './required-strings/foo.js';
+
+
+var builder = new flatbuffers.Builder();
+
+function main() {
+  testMissingFirstRequiredString();
+  builder.clear();
+  testMissingSecondRequiredString();
+}
+
+function testMissingFirstRequiredString() {
+	const undefined_string = builder.createString(undefined);
+	const defined_string = builder.createString('cat');
+
+	assert.throws(() => Foo.createFoo(
+		builder, undefined_string, defined_string
+	));
+}
+
+function testMissingSecondRequiredString() {
+	const defined_string = builder.createString('cat');
+	const undefined_string = builder.createString(undefined);
+
+	assert.throws(() => Foo.createFoo(
+		builder, defined_string, undefined_string
+	));
+}
+
+main();