Offer {Resource,Node,Domain}Ref on Jid API

This provides a non-copying API, which is generally favourable. The
other accessors were removed, because the intent was to provide this
"most sensible" API via the "default" (i.e. shortest, most concisely
named) functions.

jid/CHANGELOG.md

@@ -1,7 +1,20 @@
 Version xxx, release xxx:
+  * Breaking:
+    - With the addition of `str`-like types for `DomainPart`, `NodePart` and
+      `ResourcePart`, the functions on `Jid`, `BareJid` and `FullJid` which
+      return the respective types have been changed to return references
+      instead. Use `ToOwned::to_owned` to obtain a copy or `.as_str()` to
+      obtain a plain `str` reference.
+    - The `node_str`, `domain_str` and `resource_str` functions returning str
+      references have been removed from the JID types. Use `.as_str()` or
+      `.map(|x| x.as_str())` on the corresponding `node`/`domain`/`resource`
+      functions instead.
   * Additions:
     - Add optional quote support. Implement quote::ToTokens for Jid, FullJid
       and BareJid.
+    - `str`-like reference types have been added for `DomainPart`, `NodePart`
+      and `ResourcePart`, called `DomainRef`, `NodeRef` and `ResourceRef`
+      respectively.
 
 Version 0.10.0, release 2023-08-17:
   * Breaking