Remove unneeded spaces and commas from Json5Object.ToJson5String
Remove unneeded spaces and commas from Json5Object.ToJson5String

This fixes at least following tests:
UnquotedPropertyNamesTest
EmptyStringPropertyNamesTest
SpecialCharacterPropertyNamesTest
UnicodePropertyNamesTest
MultiplePropertiesTest
NestedObjectsTest
json5/json5-dotnet