Refactor parser tests

Refactor parser tests

Merge the PHPUnit parser test runner with the old parserTests.inc,
taking the good bits of both. Reviewed, pared down and documented the
setup code. parserTests.php is now a frontend to a fully featured
parser test system, with lots of developer options, whereas PHPUnit
provides a simpler interface with increased isolation between test
cases.

Performance of both frontends is much improved, perhaps 2x faster for
parserTests.php and 10x faster for PHPUnit.

General:

* Split out the pre-Setup.php global variable configuration from
  phpunit.php into a new class called TestSetup, also called it from
  parserTests.php.
* Factored out the setup of TestsAutoLoader into a static method in
  Maintenance.
* In Setup.php improved "caches" debug output.

PHPUnit frontend:

* Delete the entire contents of NewParserTest and replace it with a
  small wrapper around ParserTestRunner. It doesn't inherit from
  MediaWikiTestCase anymore since integrating the setup code was an
  unnecessary complication.
* Rename MediaWikiParserTest to ParserTestTopLevelSuite and made it an
  instantiable TestSuite class instead of just a static method. Got rid
  of the eval(), just construct TestCase objects directly with a
  specified name, it works just as well.
* Introduce ParserTestFileSuite for per-file setup.
* Remove parser-related options from phpunit.php, since we don't
  support them anymore. Note that --filter now works just as well as
  --regex used to.
* Add CoreParserTestSuite, equivalent to ExtensionsParserTestSuite,
  for clarity.
* Make it possible to call MediaWikiTestCase::setupTestDB() more than
  once, as is implied by the documentation.

parserTests.php frontend:

* Made parserTests.php into a Maintenance subclass, moved CLI-specific
  code to it.
* Renamed ParserTest to ParserTestRunner, this is now the generic
  backend.
* Add --upload-dir option which sets up an FSFileBackend, similar
  to the old default behaviour

Test file reading and interpretation:

* Rename TestFileIterator to TestFileReader, and make it read and buffer
  an entire file, instead of iterating.
* The previous code had an associative array representation of test
  specifications. Used this form more widely to pass around test data.
* Remove the idea of !!hooks copying hooks from $wgParser, this is
  unnecessary now that all extensions use ParserFirstCallInit. Resurrect
  an old interpretation of the feature which was accidentally broken: if
  a named hook does not exist, skip all tests in the file.
* Got rid of the "subtest" idea for tidy variants, instead use a
  human-readable description that appears in the output.
* When all tests in a file are filtered or skipped, don't create the
  articles in them. This greatly speeds up execution time when --regex
  matches a small number of tests. It may possibly break extensions, but
  they would have been randomly broken anyway since there is no
  guarantee of test file execution order.
* Remove integrated testing of OutputPage::addCategoryLinks() category
  link formatting, life is complicated enough already. It can go in
  OutputPageTest if that's a thing we really need.

Result recording and display:

* Make TestRecorder into a generic plugin interface for progress output
  etc., which needs to be abstracted for PHPUnit integration.
* Introduce MultiTestRecorder for recorder chaining, instead of using
  a long inheritance chain. All test recorders now directly inherit from
  TestRecorder.
* Move all console-related code to the new ParserTestPrinter.
* Introduce PhpunitTestRecorder, which is the recorder for the PHPUnit
  frontend. Most events are ignored since they are never emitted in the
  PHPUnit frontend, which does not call runTests().
* Put more information into ParserTestResult and use it more often.

Setup and teardown:

* Introduce a new API for setup/teardown where setup functions return a
  ScopedCallback object which automatically performs the corresponding
  teardown when it goes out of scope.
* Rename setUp() to staticSetup(), rewrite. There was a lot of cruft in
  here which was simply copied from Setup.php without review, and had
  nothing to do with parser tests.
* Rename setupGlobals() to perTestSetup(), mostly rewrite. For
  performance, give staticSetup() precedence in cases where they were
  both setting up the same thing.
* In support of merged setup code, allow Hooks::clear() to be called
  from parserTests.php.
* Remove wgFileExtensions -- it is only used by UploadBase which we
  don't call.
* Remove wgUseImageResize -- superseded by MockMediaHandlerFactory which
  I imported from NewParserTest.
* Import MockFileBackend from NewParserTest. But instead of
  customising the configuration globals, I injected services.
* Remove thumbnail deletion from upload teardown. This makes glob
  handling as in the old parserTests.php unnecessary.
* Remove math file from upload teardown, math is actually an extension
  now! Also, the relevant parser tests were removed from the Math
  extension two years ago in favour of unit tests.
* Make addArticle() private, and introduce addArticles() instead, which
  allows setup/teardown to be done once for each batch of articles
  instead of every time.
* Remove $wgNamespaceAliases and $wgNamespaceProtection setup. These were
  copied in from Setup.php in 2010, and are redundant since we do
  actually run Setup.php.
* Use NullLockManager, don't set up a temporary directory just for
  this alone.

Fuzz tests:

* Use the new TestSetup class.
* Updated for ParserTestRunner interface change.
* Remove some obsolete references to fuzz tests from the two frontends
  where they used to reside.

Bug: T41473
Change-Id: Ia8e17008cb9d9b62ce5645e15a41a3b402f4026a