make shared state thread-safe

[alivenotions]

What

The static caches in JPU (emptyListOfOnix*) were using HashMap with computeIfAbsent, which causes java.util.ConcurrentModificationException under concurrent access from multiple JonixRecords instances. switched to ConcurrentHashMap.

Continued looking to ensure other places that can also be problematic for concurrency are fixed:

• globalConfig and sourceDict to ConcurrentHashMap
• skipSourceRequested to AtomicBoolean
• event listener lists to CopyOnWriteArrayList
• fields written post-construction (onixVersion, header, encoding, etc.) to volatile

Odd thing which is maybe platform specific?

the json test fixtures had \r\n escapes baked in from a different (windows?) platform, normalized those so tests pass cleanly on a Mac and hopefully across other platforms too.