Add a times modifier that executes the test function the specified number of times

[ianwalter]

To help find flaky tests. It could look like

const { test, times } = require('@ianwalter/bff')

test('click handler', times(10), ({ expect }) => {
  let testValue = 'foo'
  const a = document.createElement('a')
  a.onclick = () => (testValue = 'bar')
  a.click()
  expect(testValue).toBe('bar')
})
``