review of printing patterns

[Janther]

spotted 2 patterns that further clean our printers:

• printGroupAndIndentIfBreakPair: usually we do have a group followed by an indentIfBreak pointing to that same group. This involves creating a Symbol. All of this can be put in the same logic.

• printIndentedGroupOrSpacedDocument: when printing (usually the body of a loop statement) we have to choose between a [' ', body] or group(indent([line, body])) this can be simplified by just having a helper with the body and a condition.

I also had a look at the printPreservingEmptyLines helper and added the logic for the comments when there are no lines. This also showed me that our printComments function was ignoring empty lines between comments.

Finally the printSeparatedItem helper has a grouped option that should always be false if the firstSeparator is a hardline