Add GraphView internal helper class, which is initialized from the Graph

but holds a more efficient and cache-friendly representation of the data
structures needed during graph traversal.

Also made faster path for main critical section for "normal" nodes not
related to control flow.

RELNOTES: Performance tuning of core graph execution module to be more
cache friendly, and to have faster paths through critical sections.

Co-author=sanjay
Change: 146368628