[php-src] Issue #23474: Ini setting to ignore `final`

Issue: https://github.com/php/php-src/issues/23474
Author: knegyesi

### Description

`final` has no technical benefit. It doesn't make a class run faster or use less memory. It's a social construct telling the users of this class the author doesn't think it should be extended. No one is clairvoyant though so all too often it turns out they did not, in fact, think of every use case. For example, maybe someone wants to use it in a test extending it and overriding only one method. 

So, there is no benefit to this "feature" and by far the best would be if it were completely ignored by the engine but I am sure purists won't let that happen so could we find a compromise here where it still exists but an ini setting turns it into functional whitespace?