Ruby AST: Extract code-related utility methods into a module
Extract Y2R::AST::Ruby::Node#wrapped_line_list
Y2R::AST::Ruby::Node#wrapped_line_list: Tweak separators

Before this commit, a separator was emitted after the last item of an
array or a hash. After this commit, it isn't. This is in line with SUSE
Ruby coding conventions.
Formatting: Split expression lists to multiple lines when needed
Formatting: Split method calls to multiple lines when needed