Pass through all options if present.

Fix: #755

Error messages now include a snippet of the document
that doesn't parse to help locate the issue, however
the way it was done wasn't UTF-8 aware, and it could
result in exception messages with truncated characters.

It would be nice to go a bit farther and actually support
codepoints, but it's a lot of complexity to do it in C,
perhaps if we move that logic to Ruby given it's not a
performance sensitive codepath.

Ensure parser error snippets are valid UTF-8

Fix JSON::GeneratorError#detailed_message with Ruby < 3.2

This works around a bug in JRuby's IOOutputStream logic whereby an
IO with an external encoding will always fail to write incoming
bytes. We use base logic to detect if the target object is a "real
IO" and if so and it has an external encoding, we drop the realIO
and. This causes the rest of IOOutputStream to avoid the fast path
and always use dyncall logic with RubyString wrappers.

This works around the issue in jruby/jruby#8682.

This should be temporary, since it will definitely degrade direct
writes to such IO objects, but a longer-term fix for the encoding
issues spelled out in jruby/jruby#8682 will need to come first,
or else json will have to be modified to not use IOOutputStream at
all.

This was the behavior until `2.10.0` unadvertently changed it.

`"\u1"` would raise, but `"\u1zzz"` wouldn't.

Raise a ParserError on all incomplete unicode escape sequence.

Fix potential out of bound read in `json_string_unescape`.