Indent assignment expressions with multi-line pipelines

[rgreenjr]

Feature Proposal

I've got this implemented. I'll issue a pull request if this proposal is approved.

Per the style guide, when assigning the result of a multi-line expression, the expression should begin on a new line.

# Bad
{found, not_found} = files
                     |> Enum.map(&Path.expand(&1, path))
                     |> Enum.partition(&File.exists?/1)


# Good
{found, not_found} =
  files
  |> Enum.map(&Path.expand(&1, path))
  |> Enum.partition(&File.exists?/1)

[lpil]

Looks good, please open a PR :)