[fuzz] Fix order of operands passed in to wasm-spec-interpreter (#4672)

In #4671, the meta-differential fuzz target was finding errors when
running certain Wasm modules (specifically `shr_s` in that case).
@conrad-watt diagnosed the issue as a missing reversal in the operands
passed to the spec interpreter. This change fixes #4671 and adds an
additional unit test to keep it fixed.

crates/fuzzing/wasm-spec-interpreter/tests/shr_s.wat

@@ -0,0 +1,9 @@
+(module
+  (type (;0;) (func (param i32 i32) (result i32)))
+  (func (;0;) (type 0) (param i32 i32) (result i32)
+    local.get 0
+    local.get 1
+    i32.shr_s
+  )
+  (export "test" (func 0))
+)