[php-src] Issue #20755: SIMPLE: Add PHP version identifier to php.ini file

Issue: https://github.com/php/php-src/issues/20755
Author: Yousha

### Description

**Problem:**
Currently, php.ini config file does **NOT** contain any explicit reference to which PHP version it is associated with. This creates several challenges:

- When users have multiple PHP versions installed (7.4, 8.0, 8.1, 8.2, 8.3), it's difficult to determine which php.ini file belongs to which version without running php --version or checking directory structures.
- During server migrations or deployments, admins might accidentally use an php.ini file from a different PHP version

**Solution:**
Add a version identifier comment at the top of the php.ini file, similar to how many config files include metadata.

```
; php.ini configuration file
; PHP Version: 8.5.0

[PHP]
; ...
```