Add dt.replace functions to specify specific day, month, year, etc. for date and datetime

[mcrumiller]

Description

The native datetime has .replace functions that allow the user to change the day, month, year, etc. to specific values:

import datetime
datetime.date(2024, 1, 1).replace(month=3, day=5)
# datetime.date(2024, 3, 5)

This would be useful for our Date and Datetime dtypes as well:

from datetime import date
import polars as pl

s = pl.Series([date(2024, 1, 31), date(2024, 5, 30)])
s.dt.replace(day=10)
# shape: (2,)
# Series: '' [date]
# [
#         2024-01-10
#         2024-05-10
# ]

This can currently be achieved via s.dt.truncate("1mo").dt.offset_by("9d") but it's a bit ugly.

[MarcoGorelli]

I think this is a duplicate of your own issue 😉 #8879
closing in favour of that one then

[mcrumiller]

Heh, sorry Marco, good find. 🤭