Fix call signature for elementor/icons_manager/additional_tabs filter

[mlwilkerson]

According to an AI code review, this code uses the wrong signature, which might result in a fatal ArgumentCountError in some versions of PHP:

add_filter( 'elementor/icons_manager/additional_tabs', fn () => $this->replace_font_awesome_additional_tabs() );

Elementor calls that filter with one arg, like this:

apply_filters( 'elementor/icons_manager/additional_tabs', $additional_tabs )

So our handler should show that it accepts that one arg.

Need to confirm whether that is actually a problem, and if so, fix it.