Fix CI: enable component_model_map in fuzzing and handle map in arbitrary_val

The fuzzer's component_api oracle was generating map types but the engine
didn't have the map feature enabled, and arbitrary_val had no arm for
Type::Map. Enable component_model_map in the store helper (matching how
component_model_async is forced on) and implement arbitrary value generation
for map types.

Author: yordis

crates/fuzzing/src/oracles/component_api.rs

@@ -118,13 +118,23 @@ fn arbitrary_val(ty: &component::Type, input: &mut Unstructured) -> arbitrary::R
                 .collect::<arbitrary::Result<_>>()?,
         ),
 
-        // Resources, futures, streams, error contexts, and maps aren't fuzzed at this time.
+        Type::Map(map) => {
+            let mut pairs = Vec::new();
+            input.arbitrary_loop(Some(MIN_LIST_LENGTH), Some(MAX_LIST_LENGTH), |input| {
+                let key = arbitrary_val(&map.key(), input)?;
+                let value = arbitrary_val(&map.value(), input)?;
+                pairs.push((key, value));
+                Ok(ControlFlow::Continue(()))
+            })?;
+            Val::Map(pairs)
+        }
+
+        // Resources, futures, streams, and error contexts aren't fuzzed at this time.
         Type::Own(_)
         | Type::Borrow(_)
         | Type::Future(_)
         | Type::Stream(_)
-        | Type::ErrorContext
-        | Type::Map(_) => {
+        | Type::ErrorContext => {
             unreachable!()
         }
     })
@@ -140,6 +150,7 @@ fn store<T>(input: &mut Unstructured<'_>, val: T) -> arbitrary::Result<Store<T>>
     config.module_config.config.max_memories = 2;
     config.module_config.component_model_async = true;
     config.module_config.component_model_async_stackful = true;
+    config.module_config.component_model_map = true;
     if config.wasmtime.compiler_strategy == CompilerStrategy::Winch {
         config.wasmtime.compiler_strategy = CompilerStrategy::CraneliftNative;
     }