Enhances SCA to process untyped region to typed region conversion.

 - RegionView and RegionViewMap is introduced to assist back-mapping from
   super region to subregions.
 - GDM is used to carry RegionView information.
 - AnonTypedRegion is added to represent a typed region introduced by pointer
   casting. Later AnonTypedRegion can be used in other similar cases, e.g.,
   malloc()'ed region.
 - The specific conversion is delegated to store manager.

llvm-svn: 59382