fix: run pest()->afterAll() hooks by flushing statics after tearDownAfterClass()

[sonalidudhia]

fix: run pest()->afterAll() hooks by flushing statics after tearDownAfterClass()

Fixes #1694

What was happening

Hooks registered via pest()->afterAll() silently never executed. The reporter
observed the hook closure showing up as a NullClosure inside
tearDownAfterClass().

Root cause

Testable::tearDown()'s finally block called $method->tearDown($this) → TestCaseMethodFactory::tearDown() →$concrete::flush(), which nulls the static self::$__afterAll after
every test. PHPUnit calls tearDownAfterClass() after the last test's
tearDown(), so by the time it runs, the static holding the afterAll hook
had already been wiped — leaving the NullClosure the reporter saw.

beforeAll doesn't have this problem because statics are populated at
instance initialization, which happens before setUpBeforeClass() ever
consumes them — there's no intervening per-test flush in that direction.

The per-test flush was also redundant: TestCaseMethodFactory::setUp()
already flushes statics before re-applying the Uses-level hook proxies for
the next test, which is what actually prevents hooks from chaining
duplicates across tests, datasets, and repetitions.

The fix

• Remove the redundant per-test flush (TestCaseMethodFactory::tearDown()
  and its call site in Testable::tearDown()) — setUp()'s pre-proxy flush
  already covers hygiene between tests.
• Move the flush into tearDownAfterClass()'s finally block, after the
  afterAll hook chain runs, so the static resets at the correct point even
  if a hook throws. Hook ordering (uses-hooks chained before the file-level
  afterAll, then parent::tearDownAfterClass()) is unchanged.

Tests

tests/Hooks/ had BeforeAllTest.php, BeforeEachTest.php, and
AfterEachTest.php, but no AfterAllTest.php — that gap is why this
regression went unnoticed. Added tests/Hooks/AfterAllTest.php.

A conventional in-test expect() assertion can't verify this hook actually
ran, because afterAll only executes after every test in the class has
finished — there's no later test to observe it from. The test instead mirrors
the shutdown-assertion pattern used in tests/Features/TestCycle.php:
register_shutdown_function() asserts the hook fired exactly once, after the
whole process (including tearDownAfterClass()) has completed.

Evidence

On 4.x HEAD (test only, source unpatched):

   PASS  Tests\Hooks\AfterAllTest
  ✓ it does not get called before all tests 1 @ repetition 1 of 2        0.01s
  ✓ it does not get called before all tests 1 @ repetition 2 of 2
  ✓ it does not get called before all tests 2

   PASS  Tests\Hooks\AfterEachTest
  ✓ nested → nested afterEach execution order                            0.06s
  ✓ global afterEach execution order

   PASS  Tests\Hooks\BeforeAllTest
  ✓ it gets called before all tests 1 @ repetition 1 of 2                0.03s
  ✓ it gets called before all tests 1 @ repetition 2 of 2
  ✓ it gets called before all tests 2

   PASS  Tests\Hooks\BeforeEachTest
  ✓ global beforeEach execution order                                    0.06s

  Tests:    9 passed (84 assertions)
  Duration: 0.94s

EXIT: 255

Pest's own reporter shows green (the per-test assertions genuinely pass — the
bug is that afterAll never runs, so there's nothing in-test to fail on).
The process still exits 255: PHPUnit's register_shutdown_function
assertion fails after the runner has already printed its summary, because
afterAllInFile stayed 0 — the hook was never invoked.

With this fix:

   PASS  Tests\Hooks\AfterAllTest
  ✓ it does not get called before all tests 1 @ repetition 1 of 2        0.01s
  ✓ it does not get called before all tests 1 @ repetition 2 of 2
  ✓ it does not get called before all tests 2

   PASS  Tests\Hooks\AfterEachTest
  ✓ nested → nested afterEach execution order                            0.03s
  ✓ global afterEach execution order

   PASS  Tests\Hooks\BeforeAllTest
  ✓ it gets called before all tests 1 @ repetition 1 of 2                0.01s
  ✓ it gets called before all tests 1 @ repetition 2 of 2
  ✓ it gets called before all tests 2

   PASS  Tests\Hooks\BeforeEachTest
  ✓ global beforeEach execution order                                    0.01s

  Tests:    9 passed (84 assertions)
  Duration: 0.22s

EXIT: 0

As a side effect, the two pest()->in('Hooks')->afterAll() hooks declared in
tests/Pest.php (which target every file in this directory, including the
new one) now actually execute for the first time — their internal
expect() assertions pass under this fix.