RUST-2256 feat: Add integration with jiff::Timestamp

[Guara92]

feat: Add interoperability with jiff::Timestamp

Hi!
This PR introduces interoperability with the jiff (docs) crate by adding helpers to convert between jiff::Timestamp and bson::DateTime. This allows users of jiff, a modern and standards-focused time library, to seamlessly serialize and deserialize timestamps with BSON, I followed the already present integration with chrono to add features and tests.

Changes included:

• Optional Dependency: Added jiff as an optional dependency under the jiff-0_2 feature flag.
• Serde Helper: Created a new serde_with helper, datetime::FromJiff02Timestamp, to enable ergonomic serialization for structs (e.g., #[serde_as(as = "datetime::FromJiff02Timestamp")]).
• Direct Conversions: Added DateTime::from_jiff() and DateTime::to_jiff() for direct, manual conversions between the two types.
• Tests: Added tests equivalent to the chrono ones

Let me know if I missed anything!

[abr-egn]

Thanks for the contribution - this looks good to me! I appreciate the care to follow the existing conventions of the bson crate 🙂. I've authorized the test run, assuming that's green I'll merge this in!

[abr-egn]

Looks like one of the tests isn't compiling:

[2025/07/31 06:31:51.209] error[E0061]: this function takes 1 argument but 2 arguments were supplied
[2025/07/31 06:31:51.209]    --> src/tests/modules/serializer_deserializer.rs:331:15
[2025/07/31 06:31:51.209]     |
[2025/07/31 06:31:51.209] 331 |     let src = jiff::Timestamp::from_second(1_286_705_410, 0).unwrap();
[2025/07/31 06:31:51.209]     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^                - unexpected argument #2 of type `{integer}`
[2025/07/31 06:31:51.209]     |
[2025/07/31 06:31:51.209] note: associated function defined here
[2025/07/31 06:31:51.209]    --> /home/ubuntu/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/jiff-0.2.15/src/timestamp.rs:619:12
[2025/07/31 06:31:51.209]     |
[2025/07/31 06:31:51.209] 619 |     pub fn from_second(second: i64) -> Result<Timestamp, Error> {
[2025/07/31 06:31:51.209]     |            ^^^^^^^^^^^

[Guara92]

serializer_deserializer

oops, my bad, I fixed another copy&paste error in one test

[isabelatkinson]

thanks for the contribution!