N - Dimensional Routed Aliases

This is a follow on from SOLR-13375, which is working for 2 dimensional cases but has some bugs remaining for 3 dimensions and up. The 2 D case is expected to be the core case and the most useful case so I'm splitting this out into it's own ticket so I can get the current code out where it can be useful, while this remaining bit is sorted out. 13375 documentation will reflect the fact that only 2 dimensions are presently supported. I do not expect any significant changes in the V1/V2 API for DRA's to enable this support.