arccore.filter should allow caller to specify a base RIS path #7

Oftentimes we leverage arccore.filter to validate/normalize some branch of a larger data structure.

For example, we may have a large deserialized JSON document and need to process just a single branch of the whole with a filter.

In cases such as this it would be nice to be able to call the filter passing in a reference to the root of the branch in the data as the filter request in-param AND also the path in the larger document that was dereferenced to obtain obtain the reference.

We would do this so that an error in the filter would get reported with the path of the data in the larger document and not as ~.blah.blah where ~ corresponds to the filter request in-param itself.

This is very confusing to developers especially when the use of the filter that returns the error is buried deep inside some large mechanism.