feat(line): add Line::raw constructor (#511)

* feat(line): add `Line::raw` constructor

There is already `Span::raw` and `Text::raw` methods
and this commit simply adds `Line::raw` method for symmetry.

Multi-line content is converted to multiple spans with the new line removed

src/text/line.rs

@@ -10,6 +10,29 @@ pub struct Line<'a> {
 }
 
 impl<'a> Line<'a> {
+    /// Create a line with the default style.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use ratatui::prelude::*;
+    /// Line::raw("test content");
+    /// Line::raw(String::from("test content"));
+    /// ```
+    pub fn raw<T>(content: T) -> Line<'a>
+    where
+        T: Into<Cow<'a, str>>,
+    {
+        Line {
+            spans: content
+                .into()
+                .lines()
+                .map(|v| Span::raw(v.to_string()))
+                .collect(),
+            alignment: None,
+        }
+    }
+
     /// Create a line with a style.
     ///
     /// # Examples
@@ -307,4 +330,15 @@ mod tests {
             ],
         );
     }
+
+    #[test]
+    fn raw_str() {
+        let line = Line::raw("test content");
+        assert_eq!(line.spans, vec![Span::raw("test content")]);
+        assert_eq!(line.alignment, None);
+
+        let line = Line::raw("a\nb");
+        assert_eq!(line.spans, vec![Span::raw("a"), Span::raw("b")]);
+        assert_eq!(line.alignment, None);
+    }
 }