fix: FileInput displaying wrong outside of Field (#29243)

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## **Description**

The `FileInput` was broken outside of its use in `Field` due to the
mapping logic being flawed. This PR fixes this by correcting the mapper.
This issue way not was not caught due to the component not being E2E
tested outside a Field.

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## **Manual testing steps**
```ts
import type { OnRpcRequestHandler } from '@metamask/snaps-sdk';
import {
  Box,
  Text,
  Bold,
  Input,
  Field,
  FileInput,
} from '@metamask/snaps-sdk/jsx';

/**
 * Handle incoming JSON-RPC requests, sent through `wallet_invokeSnap`.
 *
 * @param args - The request handler args as object.
 * @param args.origin - The origin of the request, e.g., the website that
 * invoked the snap.
 * @param args.request - A validated JSON-RPC request object.
 * @returns The result of `snap_dialog`.
 * @throws If the request method is not valid for this snap.
 */
export const onRpcRequest: OnRpcRequestHandler = async ({
  origin,
  request,
}) => {
  switch (request.method) {
    case 'hello':
      return snap.request({
        method: 'snap_dialog',
        params: {
          type: 'confirmation',
          content: (
            <Box>
              <Text>
                Hello, <Bold>{origin}</Bold>!
              </Text>
              <Text>
                This custom confirmation is just for display purposes.
              </Text>
              <Text>
                But you can edit the snap source code to make it do something,
                if you want to!
              </Text>
              <FileInput name="file-input" />
            </Box>
          ),
        },
      });
    default:
      throw new Error('Method not found.');
  }
};
```

ui/components/app/snaps/snap-ui-renderer/components/file-input.ts

@@ -6,14 +6,11 @@ export const fileInput: UIComponentFactory<FileInputElement> = ({
   element,
   form,
 }) => ({
-  element: 'SnapUIInput',
+  element: 'SnapUIFileInput',
   props: {
-    element: 'SnapUIFileInput',
-    props: {
-      name: element.props.name,
-      accept: element.props.accept,
-      compact: element.props.compact,
-      form,
-    },
+    name: element.props.name,
+    accept: element.props.accept,
+    compact: element.props.compact,
+    form,
   },
 });