Update the defaultValue check to allow for falsy and undefined values (#4838)

# Description of Changes

This fixes a bug in TypeScript table default serialization where falsy
defaults like 0, '', false, and explicit undefined were treated as if no
default was provided. I did this as a property check in order to allow
`undefined` which becomes None() as the API allows `T | undefined`.

Closes: #4700 

# API and ABI breaking changes

N/A 

# Expected complexity level and risk

1 - Simple change to check the default value was added as a property

# Testing

- [x] Reproduced the failing issue in a simple throwaway project

Author: JasonAtClockwork

crates/bindings-typescript/src/lib/table.ts

@@ -411,7 +411,8 @@ export function table<Row extends RowObj, const Opts extends TableOpts<Row>>(
       });
     }
 
-    if (meta.defaultValue) {
+    // Check for defaultValue on the property to allow for 0, false, '', and undefined as defaults
+    if (Object.prototype.hasOwnProperty.call(meta, 'defaultValue')) {
       const writer = new BinaryWriter(16);
       builder.serialize(writer, meta.defaultValue);
       defaultValues.push({