Adds gojs.MustInstantiate to avoid conflicts (#940)

This separate host from guest instantiation in ways similar to other
imports such as emscripten. Doing so allows parallel use of gojs.Run,
provided the ModuleConfig has been assigned a unique name (e.g. via an
atomic number).

Fixes #939

Signed-off-by: Adrian Cole <adrian@tetrate.io>

internal/gojs/compiler_test.go

@@ -27,6 +27,8 @@ func compileAndRun(ctx context.Context, arg string, config wazero.ModuleConfig)
 	r := wazero.NewRuntimeWithConfig(testCtx, wazero.NewRuntimeConfig())
 	defer r.Close(ctx)
 
+	gojs.MustInstantiate(ctx, r)
+
 	compiled, compileErr := r.CompileModule(ctx, testBin)
 	if compileErr != nil {
 		err = compileErr