* Fixes #8810.
* Prevent a single-line container declaration if it contains a comment
  or multiline string.
* If a container declaration cannot be single-line, ensure container
  fields are rendered with a trailing comma.
* If `Space.comma` is passed to `renderExpressionComma` or
  `renderTokenComma`, and there already exists a comma in the source,
  then render one comma instead of two.