Missing support for words with underscores and hexadecimal numbers

[RichardWGNR]

fn main() {
  let str = r#"
  {
      CP_CanFuncReqId: 0x7DF,  // 2015
  }
  "#;
  
  jsonc_parser::parse_to_serde_value(str, &Default::default()).unwrap(); // called `Result::unwrap()` on an `Err` value: ParseError(ParseErrorInner { range: Range { start: 40, end: 43 }, line_display: 4, column_display: 5, kind: UnexpectedToken })
}

1. Underscores in object properties are not parsed without framing the properties in quotes.
2. Numbers in hexadecimal notation are also not parsed.