keep orig order when merging patch

[walkthetalk]

#120 only keep key order in patch, but break order in orig.
this patch is try to keep the order both in orig and patch

[ibireme]

This test case failed:

yyjson/test/test_json_merge_patch.c

Line 77 in 06d6714

test_one("{}", "{\"a\":{\"bb\":{\"ccc\":null}}}", "{\"a\":{\"bb\":{}}}");