fix(elixir): correctly match call arguments

[calops]

Function parameters weren't correctly matched in all situations before. The previous queries seemed to be a bit complex to me and I fail to identify why, but maybe I'm missing something?

[ribru17]

I don't know if this is the right change; the elixir parser is very weird sadly (I don't know why): even in something like the following:

if a === true do
   IO.puts "Variable a is true!"
end

this entire block is parsed as a (call) node (what?)! Perhaps there is a very good reason that I am not aware of but either way it makes it difficult to just label anything in a (call) as a @parameter