bug(completions): variables leaking from for/with

[mhanberg]

Problem

variables created with the <- operator in a for expression leak outside of the block

foos = []
for foo <- foos do
 foo
end

f|

this will complete foo and foos.

Solution

This function inside _next_ls_private_compiler.ex should be changed so that it treats the call more like def/defp in the case that the last argument is is a keywordlist that has :do in it (has a do block)

In that case, the preceding 'args' are somewhat like parameters rather than arguments.

    defp expand_local(meta, fun, args, state, env) do
      # A compiler may want to emit a :local_function trace in here.
      {args, state, env} = expand_list(args, state, env)
      {{fun, meta, args}, state, env}
    end