test: support test.failing

[DonIsaac]

What is the problem this feature would solve?

Add test.failing to bun:test with the same behavior as Jest.

// foo.test.ts
describe("foo", () => {
  function foo() {
    return 2
  }

  test.failing("passes if any expectation fails or an error is thrown", () => {
    expect(foo()).toBe(1);
  })

  // this test fails
  test.failing("fails if the test 'passes': that is, no expectations fail", () => {
    expect(foo()).toBe(2)
  })

  it.failing("is also on 'it'", () => {
    expect(foo()).toBe(1)
  })
})

What is the feature you are proposing to solve the problem?

Helps developers keep track of known bugs. This is better than .todo since it forces the .failing modifier to be removed once the bug is fixed.

This also brings us closer to feature parity with Jest.

What alternatives have you considered?

No response