Add indentation following "do" completion

[aj-foster]

Related to #593, and specifically the comment by @axelson here, this PR adds a single tab¹ of indentation before the cursor after the do autocompletion.

I'm testing exclusively in VS Code, but the behavior of this change seems to be that the editor adds one relative level of indentation. So, for example, the autocompletion naturally forms the following structure (using exclusively the do completion):

defmodule Hello do
  def world do
    case something do
      # ...
    end
  end
end

It is always possible that other editors do not match this behavior. If that's the case, apologies for the confusion.

---

¹ According to sources and my experience while testing, using \t will tell VS Code to insert one TAB-worth of whichever form indentation is currently active in the editor. In my case, it correctly added two spaces.

[axelson]

Thanks for this!

It is always possible that other editors do not match this behavior. If that's the case, apologies for the confusion.

Unfortunately that is a bit true. I tested this in Emacs with lsp-mode and it added a literal tab character (which makes sense). Then I tested using two space characters instead and I'm happy to report that it fixed the indentation in Emacs and VSCode! 🎉

And I figured I'd make it an update to your PR since you went through the effort of contributing ❤️

[aj-foster]

Thank you, that's very kind! It makes sense that other editors would take it literally. Glad to know that spaces work. 👍🏼