ModelSymbolProcessorProvider

Creates the ModelSymbolProcessor of a module's KSP run, as its options say.

It does not opt the processor in to KSP's new features (backing fields and context parameters, SymbolProcessorEnvironment.registerProcessorForNewFeatures), for which KSP 2.3 warns that the processor "has not opted in for upcoming features yet". Opted in, KSP gives a property's @field: annotations (@field:AggregateId, @field:JsonProperty) to its backing field and no longer to the property, so the compiler would read them there; but KSP 2.3.13 fails with an internal error ("Unexpected null backing field symbol") when it is asked for the backing field of a property a class inherits from a library, and leaving such properties out loses their annotations. The processor opts in when KSP reads those backing fields, and its symbols are validated without the new features (me.ahoo.wow.compiler.model.symbol.isValid) until then.