This CL adds a new RegionBranchTerminatorOpInterface to query information about operands that can be passed to
successor regions. Similar to the BranchOpInterface, it allows to freely define the involved operands. However,
in contrast to the BranchOpInterface, it expects an additional region number to distinguish between various
use cases which might require different operands passed to different regions.
Moreover, we added a sample implementation to the SCF.ConditionOp to demonstrate its applicability. We also
adapted the BufferViewFlowAnalysis implementation to consider the new interface.