[Cost] Add CostKind to getVectorInstrCost and its related users

LoopUnroll estimates the loop size via getInstructionCost(),
but getInstructionCost() cannot pass CostKind to getVectorInstrCost().
And so does getShuffleCost() to getBroadcastShuffleOverhead(),
getPermuteShuffleOverhead(), getExtractSubvectorOverhead(),
and getInsertSubvectorOverhead().

To address this, this patch adds an argument CostKind to these
functions.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D142116