Checker for php.ini options

For my project I've implemented checker for php.ini options. Configuration looks like this:
```php
\App\Libraries\SelfDiagnosis\Checks\PhpIniOptions::class => [
'options' => [
'upload_max_filesize' => '>=128M',
'post_max_size' => '>=128M',
'memory_limit' => '>=128M',
'max_input_vars' => '>=10000',
'file_uploads' => '1',
'disable_functions' => '',
],
],
```

If project owners will be interested, I can send PR

Start by reviewing the existing self-diagnosis checks and the proposed App\Libraries\SelfDiagnosis\Checks\PhpIniOptions class. Compare the listed php.ini options and operators with the project's current checker configuration. Done means the checker can evaluate those options and the expected configuration is covered by verification.

Written by the indexing model from the issue text.