Add cookie management to axum-extra (#816)

* Cookie management

* fix feature

* Update axum-extra/src/extract/cookie.rs

Co-authored-by: Jonas Platte <[email protected]>

* add tests

* Apply suggestions from code review

Co-authored-by: Jonas Platte <[email protected]>

* less convoluted wording

* changelog

* Make the jars themselves implement `IntoResponseParts`

* dedup tests

* fix docs

Co-authored-by: Jonas Platte <[email protected]>

axum-extra/src/extract/mod.rs

@@ -1,5 +1,10 @@
 //! Additional extractors.
 
 mod cached;
+#[cfg(feature = "cookie")]
+pub mod cookie;
 
 pub use self::cached::Cached;
+
+#[cfg(feature = "cookie")]
+pub use self::cookie::{CookieJar, SignedCookieJar};