Improve event value cache

[UnderscoreTud]

Problem

The event value registry doesn't take into account event validators when caching event value resolutions, this causes issues when an event value relies on external factors that are not constrained to just the event class. For example, skript-reflect's custom events register one skript event and rely on the identifier to figure out which custom event's logic to use. This causes Skript to wrongly cache event values as successful/failure and use the same cached result for all subsequent calls for that event value, no matter the custom event.

Solution

Include an option to exclude an event value from being cached if it depends on external contexts.

Testing Completed

EventValueRegistryTest.java

Supporting Information

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Completes: none
Related: none
AI assistance: junie for writing most test cases