Update $string with new fast-json-stringify asString

[cesco69]

Update $string with new fast-json-stringify asString

[samchon]

Tested, but performance be slowed.

Before

Types	typia.stringify	typia.isStringify	typia.assertStringify	fast-json-stringify	JSON.stringify	class-transformer
object (simple)	2,197	1,822	1,734	719	121	9.41
object (hierarchical)	784	763	747	916	182	19
object (recursive)	1,002	963	933	864	185	17
object (union, explicit)	310	256	263	209	120	7.20
array (simple)	376	354	356	607	235	18
array (hierarchical)	447	458	453	803	196	14
array (recursive)	400	388	378	832	192	16
array (union, explicit)	334	315	323	76	256	15

After

Types	typia.stringify	typia.isStringify	typia.assertStringify	fast-json-stringify	JSON.stringify	class-transformer
object (simple)	1,913	1,712	1,612	651	113	9.44
object (hierarchical)	681	698	743	653	170	19
object (recursive)	800	695	541	643	148	13
object (union, explicit)	222	179	181	157	98	5.49
array (simple)	291	266	279	435	178	14
array (hierarchical)	324	302	308	562	163	10
array (recursive)	304	269	284	637	167	13
array (union, explicit)	249	239	234	61	210	12