Consistent indentation for test files

Hi internals, Right now we do not have a consistent standard for the indentation of PHPT files. Some people create space-indented files, others create tab-indented files. Over time, indentation invariably starts to mix, because developers with different indentation settings work on one file. Here are the current statistics for code in .phpt files: total: 15515 prefer tabs: 4273 (27.5%) prefer spaces: 6307 (40.7%) draw: 77 (0.5%) no indentation: 4858 (31.3%) There are 1824 (11.8%) files that contain mixed tab and space indentation. The indentation was determined based on the first character of a line. I would like to propose that we establish a common standard by a) using space indentation for all future tests (as they currently form the majority), and b) reindenting existing test files to use space indentation. Thanks, Nikita PS: Motivated by https://github.com/php/php-src/pull/2879. PRs regularly have WS issues.