Fix error suppression for PHP 8+ (#16615)

### What does it do?
Adds a check to the custom error handler function, to see if a warning
has to be handled.

### Why is it needed?
MODX has a custom error handler function. When the error control
operator (`@`) is used (e.g. `@exif_read_data()`), the custom error
handler still gets called.

With **PHP 7.4,** when the error was suppressed by the `@` operator,
`error_reporting()` called inside the custom error handler always
returned 0. This gets checked here:


https://github.com/modxcms/revolution/blob/9e7bb63615f8a9921e657027501f2aaf1be07454/core/src/Revolution/Error/modErrorHandler.php#L61-L63

With **PHP 8**, this is no longer the case:
> As of PHP 8.0.0, it returns the value of this (bitwise) expression:
E_ERROR | E_CORE_ERROR | E_COMPILE_ERROR | E_USER_ERROR |
E_RECOVERABLE_ERROR | E_PARSE.

https://www.php.net/manual/en/language.operators.errorcontrol.php

### How to test

For example:
- Use PHP 8.0 (or higher)
- Open the media browser and navigate to a folder with a picture that
doesn't have EXIF headers.
- Make sure, that the warning `PHP warning: exif_read_data(...): File
not supported` doesn't get logged to the MODX error log anymore.

### Related issue(s)/PR(s)
#16420

core/src/Revolution/Error/modErrorHandler.php

@@ -58,7 +58,7 @@ function __construct(modX &$modx, array $stack = [])
      */
     public function handleError($errno, $errstr, $errfile = null, $errline = null, $errcontext = null)
     {
-        if (error_reporting() == 0) {
+        if (error_reporting() == 0 || !(error_reporting() & $errno)) {
             return false;
         }