Add a php_phpcbf_options conf equivalent to php_phpcs_options

I'm currently in a position where I need `php_phpcs_options` to enable linting on file extensions not defaulted in the standard. This works for linting but currenlty ALEFix will not work with phpcbf because I can't set the options to set the correct extensions. There should be parity in these options since they're largely the same project.

```
let g:ale_php_phpcs_options="--extensions=php,module,inc,install,info" # works
let g:ale_php_phpcbf_options="--extensions=php,module,inc,install,info" # no support currently.
```