feat(tui-big-text): add alignment helper methods

Adds helper methods to the `BigTextBuilder` struct to set the alignment
of the text. This makes it simpler to set the alignment of the text.

```rust
let left = BigText::builder()
    .left_aligned()
    .lines(vec!["Left".white().into()])
    .build()?;

let right = BigText::builder()
    .right_aligned()
    .lines(vec!["Right".green().into()])
    .build()?;

let centered = BigText::builder()
    .centered()
    .lines(vec!["Centered".red().into()])
    .build()?;
```

Author: joshka

tui-big-text/examples/alignment.rs

@@ -1,7 +1,7 @@
 use color_eyre::Result;
 use ratatui::{
     layout::Offset,
-    prelude::{Alignment, Frame, Stylize},
+    prelude::{Frame, Stylize},
     text::Line,
 };
 use tui_big_text::{BigText, PixelSize};
@@ -21,19 +21,19 @@ fn render(frame: &mut Frame) -> Result<()> {
 
     let left = BigText::builder()
         .pixel_size(PixelSize::Quadrant)
-        .alignment(Alignment::Left)
+        .left_aligned()
         .lines(vec!["Left".white().into()])
         .build()?;
 
     let right = BigText::builder()
         .pixel_size(PixelSize::Quadrant)
-        .alignment(Alignment::Right)
+        .right_aligned()
         .lines(vec!["Right".green().into()])
         .build()?;
 
     let centered = BigText::builder()
         .pixel_size(PixelSize::Quadrant)
-        .alignment(Alignment::Center)
+        .centered()
         .lines(vec!["Centered".red().into()])
         .build()?;
 

tui-big-text/src/big_text.rs

@@ -85,6 +85,23 @@ impl BigText<'static> {
     }
 }
 
+impl BigTextBuilder<'_> {
+    /// Set the alignment of the text.
+    pub fn left_aligned(&mut self) -> &mut Self {
+        self.alignment(Alignment::Left)
+    }
+
+    /// Set the alignment of the text.
+    pub fn right_aligned(&mut self) -> &mut Self {
+        self.alignment(Alignment::Right)
+    }
+
+    /// Set the alignment of the text.
+    pub fn centered(&mut self) -> &mut Self {
+        self.alignment(Alignment::Center)
+    }
+}
+
 impl Widget for BigText<'_> {
     fn render(self, area: Rect, buf: &mut Buffer) {
         let layout = layout(area, &self.pixel_size, self.alignment, &self.lines);