Add RegionBuilder to TOSA MLIR Translator

Rationale for making this change:
- The original design only supports a single basicBlock which is no
longer functionaly enough to support Control Flow operators like WhileOp
or IFOp
- Added another layer of abstraction of Region to support multiple
basicBlocks + other corresponding fixes
- There are other companion patches to make the above proposal work
  - Serialization Lib: Add TosaSerializationRegion to serialization_lib
  - Reference Model: Reference model update for control flow

Signed-off-by: Jerry Ge <jerry.ge@arm.com>
Change-Id: Ic7eec3c32da87d409819365ba2dc7ef8b9619db4