[php-src] Issue #24112: Improve the reporting of parsing errors

Issue: https://github.com/php/php-src/issues/24112 Author: David263 ### Description (I'm posting here to capture this idea, as I don't have the time to shepherd the steps of a formal RFC request.) Currently, a parse error is reported to an error file and an HTTP 500 error is raised by all recent versions of PHP, unless php.ini is changed (which is not always possible, and which might require distinguishing between production and development access, which is currently not supported except by workarounds like using an environment variable). Reporting error settings are ignored. There is no perfect workaround available via .htaccess under Apache. There is a workaround: changing all main programs to include/require the real main programs, but this is arguably ugly and adds to the learning hurdle. These problems could be solved by a rewrite of the parser and how the parser is called, so it works like many other interpreters or compilers. It could be argued that this is a major change that would impact many users. However, major changes that impact more users than would be impacted by this change have already been done. An example is the mysql_* removal (deprecated in 5.5, gone in 7.0). This required rewriting almost all MySQL code, an incredible impact, justified only by a perceived urgent need to increase security. And there were other PHP changes that involved deprecation with much, much lower urgency, such as the $string{0} curly-brace offset syntax being removed in 8.0 after a deprecation period. Reporting parsing errors in the same way as other errors would benefit far more users than it would burden, by improving the reporting of this category of error and by reducing the PHP learning hurdle and several maintenance impacts.