jsonc serialization support

**Is your feature request related to a problem? Please describe.**

> Currently, this module only provides a means of parsing JSONC. JSONC serialization is not yet supported.

i'd like to be able to serialize object into JSONC with comments such as

```ts
const foo = { a: 1, b: 2 }

JSONC.stringify(foo)
//=> `{
// "a":1,
// "b":2,
// }`
```

**Describe the solution you'd like**

add `stringify` to `@std/jsonc`

**Describe alternatives you've considered**