Expose richer IOperation API for queries

[mavasani]

We currently expose an ITranslatedQueryOperation to represent the high level operation node generated for a query expression. This issue tracks design and implementation of richer IOperation API, with possible design alternatives:

1. Enhance the subtree of an ITranslatedQueryOperation. For example, by wrapping translated invocation nodes for clauses with new query clause operation nodes.
2. Expose a non-translated or non-lowered query operation tree and expose it instead of the translated query operation. This is a substantially huge work item.