Implement Set Operators for Box Types

[chaitan94]

• +: Union of the bounding boxes
• *: Intersection of the bounding boxes

We can override the respective operators in both C++ and Python
Invalid operations should throw accordingly

Todo Checklist

• TBox, TBox
  • Union
  • Intersection
• STBox, STBox
  • Union
  • Intersection

MobilityDB queries for reference/test cases

mobilitydb=# select intrange '[10, 20)' + '[15, 40)';
 ?column? 
----------
 [10,40)
(1 row)

mobilitydb=# select intrange '[10, 20)' * '[15, 40)';
 ?column? 
----------
 [15,20)
(1 row)

mobilitydb=# select intrange '[10, 20)' - '[15, 40)';
 ?column? 
----------
 [10,15)
(1 row)

mobilitydb=# select intrange '[10, 20)' + '[30, 40)';
ERROR:  result of range union would not be contiguous