Currently, as part of SERVER-23172 collated queries will disallow use of a collated index if query bounds contain an object or array, even if the bounds do not contain a nested string.

We should consider recursively exploring the bounds to determine if they do in fact contain a string. Currently we are excessively strict in requiring index collation to match query-collation on certain queries.

This behavior also affects covering analysis.

The CollationIndexKey class is responsible for key translation and determining whether a given element requires a collation-aware index key.