Allow customization of Interpolator used for BaseFilter.getDefaultFilterWrappers(...)

The default implementation of getDefaultFilterWrappers always returns a single element list containing a Wrapper (https://github.com/apache/maven-filtering/blob/9d528d0871d93e317ae21a4b6922cd795502364c/src/main/java/org/apache/maven/shared/filtering/BaseFilter.java#L178).
That Wrapper's Interpolator should be customizable with regards to

1. ValueSource and
2. InterpolationPostProcessor

Currently neither the Interpolator nor the Wrapper class is exposed or can be extended.

As not every DefaultFilterInfo implementation necessarily relies on the Plexus Interpolator this should probably be part of a dedicated interface which is only implemented for Interpolator based default filters.