Add *.wast support for invoking components (#4526)

This commit builds on bytecodealliance/wasm-tools#690 to add support to
testing of the component model to execute functions when running
`*.wast` files. This support is all built on #4442 as functions are
invoked through a "dynamic" API. Right now the testing and integration
is fairly crude but I'm hoping that we can try to improve it over time
as necessary. For now this should provide a hopefully more convenient
syntax for unit tests and the like.

crates/fuzzing/src/generators/table_ops.rs

@@ -3,8 +3,9 @@
 use arbitrary::{Arbitrary, Result, Unstructured};
 use std::ops::RangeInclusive;
 use wasm_encoder::{
-    CodeSection, EntityType, ExportKind, ExportSection, Function, FunctionSection, GlobalSection,
-    ImportSection, Instruction, Module, TableSection, TableType, TypeSection, ValType,
+    CodeSection, ConstExpr, EntityType, ExportKind, ExportSection, Function, FunctionSection,
+    GlobalSection, ImportSection, Instruction, Module, TableSection, TableType, TypeSection,
+    ValType,
 };
 
 /// A description of a Wasm module that makes a series of `externref` table
@@ -94,7 +95,7 @@ impl TableOps {
                     val_type: wasm_encoder::ValType::ExternRef,
                     mutable: true,
                 },
-                &Instruction::RefNull(wasm_encoder::ValType::ExternRef),
+                &ConstExpr::ref_null(wasm_encoder::ValType::ExternRef),
             );
         }