text: ensure truncated consecutive newlines are handled

This commit ensures that multiple newlines in a row still produce expected
results when occuring within a truncated string. The problem was that we usually
wrap text that is truncated in a way that forces the truncator symbol to appear
at the end *unless* we know we're on the final paragraph of the input text. This
is the right behavior for text that will be displayed, but when shaping a paragraph
containing nothing but a newline, we do not want the truncator symbol in our line.
I simply had to disable the forced truncation contextually to make it work.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

text/gotext.go

@@ -530,6 +530,7 @@ func (s *shaperImpl) LayoutRunes(params Parameters, txt []rune) document {
 	}
 	truncatedNewline := false
 	if hasNewline && len(txt) == 0 {
+		params.forceTruncate = false
 		// If we only have a newline, shape a space to get line metrics.
 		ls, truncated = s.shapeAndWrapText(params, []rune{' '})
 		if truncated > 0 {