[JS] `run()` doesn't pass the input to the passed function

[lacolaco]

Describe the bug

run() doesn't pass the input to the passed function.

This is caused by checking arguments.length in the run() implementation. That condition is always falsy.

genkit/js/core/src/flow.ts

Lines 200 to 204 in f18da1f

	async (meta) => {
	meta.input = input;
	const output = arguments.length === 3 ? await func(input) : await func();
	meta.output = JSON.stringify(output);
	return output;

To Reproduce

    it('should run the action', async () => {
      const act = async () => 'bar';

      const result = await run('action', act, registry);

      assert.equal(result, 'bar'); // => OK
    });

    it('should run the action with input', async () => {
      const act = async (input: string) => `${input} bar`;

      const result = await run('action', 'foo', act, registry);

      assert.equal(result, 'foo bar'); // => ERROR `undefined bar`.
    });

Expected behavior

Tests the above should pass.

Screenshots
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Runtime (please complete the following information):

• OS: [e.g. Linux, MacOS]
• Version [e.g. 22]

** Node version

• run node --version at paste here

Additional context