Renames preparatory to parser tests refactor

Renames preparatory to parser tests refactor

Since in several cases, with an all-in-one commit, git's file rename
detection failed, I split the renames out into their own commit to
make review easier. Some changes here won't make complete sense without
the following commit.

* Moved TestsAutoLoader to tests/common/. It will be joined by a friend.
* Renamed ParserTest to ParserTestRunner, since the former name was
  overly generic.
* Renamed TestFileIterator to TestFileReader. Please see the subsequent
  commit for rationale.
* Moved parserTests.php to tests/parser/. It was the only file left in
  tests/, and it should have been moved to tests/parser years ago,
  analogous to phpunit.php.
* Renamed NewParserTest to ParserIntegrationTest. This was a tricky one,
  apparently the name has to end in "Test" or else the structure test
  will fail. Analogous to ParserMethodsTest etc. Rationale: because it's
  not new anymore.
* Renamed MediaWikiParserTest to ParserTestTopLevelSuite and moved it to
  the suites directory. A more descriptive name. Being in suites/
  shields it from StructureTests, and is correct anyway.

Change-Id: Iddc6eaf815fdd64b3addb8570b4b6303ab99d634