errors: generate typed identifiers in each crate

Instead of loading the Fluent resources for every crate in
`rustc_error_messages`, each crate generates typed identifiers for its
own diagnostics and creates a static which are pulled together in the
`rustc_driver` crate and provided to the diagnostic emitter.

Signed-off-by: David Wood <david.wood@huawei.com>

compiler/rustc_interface/src/util.rs

@@ -59,6 +59,7 @@ pub fn create_session(
     sopts: config::Options,
     cfg: FxHashSet<(String, Option<String>)>,
     check_cfg: CheckCfg,
+    locale_resources: &'static [&'static str],
     file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
     io: CompilerIO,
     lint_caps: FxHashMap<lint::LintId, lint::Level>,
@@ -94,6 +95,7 @@ pub fn create_session(
         io,
         bundle,
         descriptions,
+        locale_resources,
         lint_caps,
         file_loader,
         target_override,