Support `@JsonAnySetter` on setter method (single `Map` parameter)

^{Originally posted by **chrylis** January 7, 2025}
Currently, `@JsonAnySetter` can be used on a physical field of type `Map`, but unlike `@JsonProperty`, it will be silently dropped if used on a method of arity other than two (`POJOPropertiesCollector#_addMethods`). I would like to be able to use `@JsonAnySetter` on a method representing a virtual property, like this:

```
@Slf4j
class WebhookDto {
@JsonAnySetter
void setUnmappedProperties(Map unmapped) {
log.warn("unmapped properties on webhook: {}", unmapped)
}
}
```