Performance improvements in `ReactiveWrappers` and `ConvertingPropertyAccessor`

[mp911de]

ReactiveWrappers.isAvailable() performs repetitive checks on classpath availability and supports(…) could cache the outcome on a per-type basis to avoid looping through the registry.

ConvertingPropertyAccessor.convertIfNecessary(…) should avoid calling the conversion service if the target type is a primitive by using ClassUtils.resolvePrimitiveIfNecessary(type).

Findings originate from spring-projects/spring-data-cassandra#1218.