More lenient lifetime bound in `SliceJsonParser::parse_next`

Some renaming to get a cleaner API (aliases with the old names are kept): - `FromTokioAsyncReadJsonReader` -> `TokioAsyncReaderJsonParser` - `FromBufferJsonReader` -> `SliceJsonParser` - `FromReadJsonReader` -> `ReaderJsonParser` - `LowLevelJsonReader` -> `LowLevelJsonParser` - `LowLevelJsonReaderResult` -> `LowLevelJsonParserResult` - `ParseError` -> `JsonParseError` - `SyntaxError` -> `JsonSyntaxError` - `ToTokioAsyncWriteJsonWriter` -> `TokioAsyncWriterJsonSerializer` - `ToWriteJsonWriter` -> `WriterJsonSerializer<W>` - `LowLevelJsonWriter` -> `LowLevelJsonSerializer` - `read_next_event` -> `parse_next` - `write_event` -> `serialize_event`

- The parser API has been rewritten. The new entry points are `FromBufferJsonReader`, `FromReadJsonReader`, and `LowLevelJsonReader`. - The serializer API has been rewritten. The new entry points are `ToWriteJsonWriter` and `LowLevelJsonWriter`. - The parser now returns `ParseError` and `SyntaxError` types instead of `std::io::Error`. - Added support of UTF-8 byte-order-mark (BOM) during parsing. - Added support of Tokio `AsyncRead` and `AsyncWrite` interfaces behind the `async-tokio` feature. - Escaped unicode surrogate pairs are now carefully validated. - Minimal supported Rust version has been bumped to 1.70.

- The parser API has been rewritten. The new entry points are `FromBufferJsonReader`, `FromReadJsonReader`, and `LowLevelJsonReader`. - The serializer API has been rewritten. The new entry points are `ToWriteJsonWriter` and `LowLevelJsonWriter`. - The parser now returns `ParseError` and `SyntaxError` types instead of `std::io::Error`. - Added support of UTF-8 byte-order-mark (BOM) during parsing. - Added support of Tokio `AsyncRead` and `AsyncWrite` interfaces behind the `async-tokio` feature. - Escaped unicode surrogate pairs are now carefully validated. - Minimal supported Rust version has been bumped to 1.70.