Fix type annotations in pandas.tseries.*
Part of #25882

pandas.tseries files currently have these errors:
```
pandas/tseries/frequencies.py:40: error: Need type annotation for '_offset_map'

pandas/tseries/holiday.py:332: error: Need type annotation for 'rules'

pandas/tseries/offsets.py:1656: error: Incompatible types in assignment (expression has type "int", base class "QuarterOffset" defined the type as "None")
pandas/tseries/offsets.py:1657: error: Incompatible types in assignment (expression has type "int", base class "QuarterOffset" defined the type as "None")
pandas/tseries/offsets.py:1666: error: Incompatible types in assignment (expression has type "int", base class "QuarterOffset" defined the type as "None")
pandas/tseries/offsets.py:1667: error: Incompatible types in assignment (expression has type "int", base class "QuarterOffset" defined the type as "None")
pandas/tseries/offsets.py:1681: error: Incompatible types in assignment (expression has type "int", base class "QuarterOffset" defined the type as "None")
pandas/tseries/offsets.py:1688: error: Incompatible types in assignment (expression has type "int", base class "QuarterOffset" defined the type as "None")
pandas/tseries/offsets.py:1689: error: Incompatible types in assignment (expression has type "int", base class "QuarterOffset" defined the type as "None")
```
I have added annotations to address these issues and removed the modules from mypy.ini. PR to follow presently.