ENH: Support for "52–53-week fiscal year" / "4–4–5 calendar" and LastWeekOfMonth DateOffset

Closes #4511 and #4637

- Added ``LastWeekOfMonth`` DateOffset #4637
- Added ``FY5253``, and ``FY5253Quarter`` DateOffsets #4511
- Improved error handling in ```get_freq_code```, ```_period_str_to_code``` and ```_base_and_stride```
- Fix issue with datetime - Timestamp