Serde support improvements and bugfix

What's Changed

New Features

• #609: Added Writer::write_serializable to provide the capability to serialize arbitrary types using serde when using the lower-level Writer API.
• #615: Added Deserializer::from_str_with_resolver to set entity resolver when deserialize using borrowing reader.
• #617: Added Serializer::expand_empty_elements to enforce the expansion of empty elements.

Bug Fixes

• #604: Avoid crashing on wrong comments like <!--> when using read_event_into* functions.

Misc Changes

New Contributors

• @bahlo made their first contribution in #620

Full Changelog: v0.29.0...v0.30.0