Add support for const inputs in runner_util (#1810)

Summary:

These are all valid input types now in an Executorch program.

Differential Revision: D53335087

Author: tarun292

extension/runner_util/inputs.cpp

@@ -23,11 +23,18 @@ Result<BufferCleanup> prepare_input_tensors(Method& method) {
   void** inputs = (void**)malloc(num_inputs * sizeof(void*));
 
   for (size_t i = 0; i < num_inputs; i++) {
-    Result<TensorInfo> tensor_meta = method_meta.input_tensor_meta(i);
-    if (!tensor_meta.ok()) {
+    auto tag = method_meta.input_tag(i);
+    if (!tag.ok()) {
+      return tag.error();
+    }
+    if (tag.get() != Tag::Tensor) {
       ET_LOG(Info, "Skipping non-tensor input %zu", i);
       continue;
     }
+    Result<TensorInfo> tensor_meta = method_meta.input_tensor_meta(i);
+    if (!tensor_meta.ok()) {
+      return tensor_meta.error();
+    }
     // This input is a tensor. Allocate a buffer for it.
     void* data_ptr = malloc(tensor_meta->nbytes());
     inputs[num_allocated++] = data_ptr;