wasmparser: Fix subtyping depth indexing

fix: #1967

This patch addresses an issue in subtyping depth checking
where `set_subtyping_depth` indexes the depth by `CoreTypeId`,
but `get_subtyping_depth` accesses it using `CoreTypeId#index` (`u32`).
This leads to "IndexMap: index out of bounds" error when validating
WasmGC components with subtypes.

However, I have no idea why this issue occurs specifically in WasmGC components
and not in WasmGC modules.

crates/wasmparser/src/validator/types.rs

@@ -995,7 +995,7 @@ impl TypeList {
         let depth = self
             .core_type_to_depth
             .as_ref()
-            .expect("cannot get subtype depth from a committed list")[id.index()];
+            .expect("cannot get subtype depth from a committed list")[&id];
         debug_assert!(usize::from(depth) <= crate::limits::MAX_WASM_SUBTYPING_DEPTH);
         depth
     }