Rename "timezone-display::name" to "id"

Other possibilities: "tzid", "iana-id", "identifier", "iana-identifier".

Returning a user-displayable name as part of timezone-display would
require more information: the user's preferred language, and the preferred
style for the name:
 - abbreviated or not
 - year-round or specific to the Instant
E.g., the time zone with the IANA id "America/Los_Angeles" might be
displayed as "Pacific Time", "Pacific Standard Time", "Pacific Daylight
Time", "PT", "PST", "PDT", "Nordamerikanische Westküstenzeit"...

The Rust iana_time_zone crate uses IANA time zone IDs, so if this
interface needs to be able to implement iana_time_zone, timezone-display
should have an IANA ID and not a user-displayable name.

Author: ptomato

README.md

@@ -96,7 +96,7 @@ default-monotonic-clock: monotonic-clock
 
     let timezone_display: TimezoneDisplay = timezone::display(instant);
 
-    println!("the timezone is {}", timezone_display.name);
+    println!("the timezone is {}", timezone_display.id);
 ```
 
 ### Detailed design discussion

wit-0.3.0-draft/timezone.wit

@@ -32,15 +32,18 @@ interface timezone {
         /// should return 0.
         utc-offset: s32,
 
-        /// The abbreviated name of the timezone to display to a user. The name
-        /// `UTC` indicates Coordinated Universal Time. Otherwise, this should
-        /// reference local standards for the name of the time zone.
+        /// The IANA identifier of the timezone. The id `UTC` indicates
+        /// Coordinated Universal Time. Otherwise, this should be an identifier
+        /// from the IANA Time Zone Database.
+        ///
+        /// For displaying to a user, the identifier should be converted into a
+        /// localized name by means of an internationalization API.
         ///
         /// In implementations that do not expose an actual time zone, this
         /// should be the string `UTC`.
         ///
         /// In time zones that do not have an applicable name, a formatted
         /// representation of the UTC offset may be returned, such as `-04:00`.
-        name: string,
+        id: string,
     }
 }