Add more Debug implementations

I generally like to implement Debug on these kind of types.

src/buffer_line.rs

@@ -4,6 +4,7 @@ use alloc::{string::String, vec::Vec};
 use crate::{Align, AttrsList, FontSystem, LayoutLine, ShapeLine, Shaping, Wrap};
 
 /// A line (or paragraph) of text that is shaped and laid out
+#[derive(Debug)]
 pub struct BufferLine {
     //TODO: make this not pub(crate)
     text: String,