EventDispatchContext compatibility with Threads ReadWriteMutex

[LK-Simon]

Problem

Event<T> stores its dispatch context using:

Threads::ReadWriteMutex<
    EventDispatchContext
>

ESPressio Threads 3.1 uses equality comparison as part of the default ReadWriteMutex<T> change-detection mechanism.

EventDispatchContext, however, does not currently provide equality semantics.

Consequently, template instantiation of the relevant ReadWriteMutex<EventDispatchContext> path can fail because the default comparator attempts to evaluate:

a == b

for two EventDispatchContext instances.

Expected behaviour

EventDispatchContext should be equality-comparable under the project's C++17 target.

Two dispatch contexts should be considered equal when all values describing the dispatch context are equal:

• Origin
• TransportMessageID
• HopCount

This allows ReadWriteMutex<EventDispatchContext> to use its normal change-detection mechanism without requiring a special-case comparator or weakening the generic Threads implementation.

Compatibility

The fix should be entirely backward-compatible.

No Event dispatch, Event Transport, listener, Observer, Event Bridge, or runtime Serializable Event interfaces should require modification.