DOC: Fix docstrings for Timestamp: strptime, timetz, to_datetime64, to_julian_date
Part of #59458

Addresses:

pandas.Timestamp.strptime PR01,SA01
pandas.Timestamp.timetz SA01
pandas.Timestamp.to_datetime64 SA01
pandas.Timestamp.to_julian_date ES01

Changes:
Edited Short Summary of strptime
Added See Also, Extended Summary, Parameters to strptime
Added See Also, Extended Summary to timetz
Edited Short Summary of to_datetime64
Added See Also, Extended Summary to to_datetime64
Edited Extended Summary of to_julian_date
Removed 3 of 4 methods from code_checks.sh (to_julian_date not in the file)
Thanks @jsngn 