Add conversion support for the jiff datetime library

[rumpelsepp]

The author of ripgrep has started a datetime library called jiff. The author provides a in depth comparison with other datetime libraries here. I figure, jiff might gain popularity quickly and it could be a good improvement for pyo3 to provide an implementation for converting to python datetime objects (as it is available for, e.g., chrono).

[bschoenmaeckers]

Sounds like a great exercise. I maybe take a stab at this next week.

[jessekrubin]

I haven't done the conversions (tho I can add them), BUT I did add jiff struct wrappers to my to my side project recently if you are interested in checking it out https://github.com/jessekrubin/ry/blob/main/crates/ryo3-jiff/src

The project is a set of thin(ish) wrappers around several crates.

UPDATE/EDIT:

In my spare time I was able to make almost all the conversions (same repo) -- the conversions use new-type pattern with super thin wrapper structs around the jiff structs to get around the batman-rule (orphan-rule) so it might be a good base for really PR-ing in the jiff-type conversions.

I have little to no tests for the conversions in rust, all my tests are in python.

[jessekrubin]

I will also add that jiff has been an absolute delight to work with.