Improve the performance for JAXB data format

We should use the ServicePool in camel-core to pool JAXB / marshaller / unmarshaller.
Of course ppl should be able to customize pool settings and if to be used.

Also mind that for type converters with JAXB you do not configure a JAXB data format. And thus we should
still be able to configure and use pooling, so the type converter can be more efficient.