Fix problem preventing the compilation using arara

[mms-neuro]

This fixes #2861 - and makes compilation with arara possible again.

I also renamed opts to passed_options to be more consistent with the naming in other compile methods (e.g.

vimtex/autoload/vimtex/compiler/latexmk.vim

Line 135 in 9308048

function! s:compiler.__build_cmd(passed_options) abort dict " {{{1

).

[lervag]

Thanks! <3