ShapedLines are never wrapped, whereas WrappedLines are optionally
wrapped if they are associated with a wrap width. Originally, when
rewriting GPUI, I tried to combine everything because wrapping is
inherently optional for the Text element, but we have a bunch of APIs
that don't make sense on a line that may wrap, so we need a distinct
type for that case.

This is a precursor to implementing clickable links in markdown. I
noticed multiple places where we were confused about whether or not the
line was wrapped so this felt important.

Release Notes:

- N/A