Preserve at most a single empty line between attributes

[awalterschulze]

After receiving multiple issues with not preserving empty lines between attributes: from ifdef, ifdef with spec above, emulator args and trying to remove newlines between attributes with the same name, maybe these rules are becoming to complicated, here are links to some of the issues: #205 #95 #59 #178

erlfmt is an opinionated formatter, but at some points it has to leave some formatting up to the users.
We will stop removing an empty line between attributes like we have done before and we will stop adding an empty line between some attributes.

For example, this is not validly formatted code right now, but would be after we make this change.

-module(bla).
-define(DEFAULT_WIDTH, 100).