[Fix #1075] More strict limits on when to require trailing comma

When TrailingComma:EnforcedStyleForMultiline is comma, we only
report an offense if each value in the list is on its own line,
and the closing round/square/curly bracket is also on its own line
(as opposed to sharing a line with the last value).
Merge pull request #1121 from jonas054/1075_trailing_comma

[Fix #1075] More strict limits on when to require trailing comma