feat: Add gum style command

Style provides a shell script interface for Lip Gloss. It allows you to
use Lip Gloss to style text without needing to use Go. All of the
styling options are available as flags.

Let's make some text glamorous using bash:

```
gum style \
    --foreground "#FF06B7" --border "double" \
    --margin 2 --padding "2 4" --width 50 \
    "And oh gosh, how delicious the fabulous frizzy frobscottle" \
    "was! It was sweet and refreshing. It tasted of vanilla and" \
    "cream, with just the faintest trace of raspberries on the" \
    "edge of the flavour. And the bubbles were wonderful."
```

Output:

```
╔══════════════════════════════════════════════════╗
║                                                  ║
║                                                  ║
║    And oh gosh, how delicious the fabulous       ║
║    frizzy frobscottle was It was sweet and       ║
║    refreshing. It tasted of vanilla and          ║
║    cream, with just the faintest trace of        ║
║    raspberries on the edge of the flavour.       ║
║    And the bubbles were wonderful.               ║
║                                                  ║
║                                                  ║
╚══════════════════════════════════════════════════╝
```

style/align.go

@@ -0,0 +1,12 @@
+package style
+
+import "github.com/charmbracelet/lipgloss"
+
+// align maps strings to `lipgloss.Position`s
+var align = map[string]lipgloss.Position{
+	"center": lipgloss.Center,
+	"left":   lipgloss.Left,
+	"top":    lipgloss.Top,
+	"bottom": lipgloss.Bottom,
+	"right":  lipgloss.Right,
+}

style/borders.go

@@ -0,0 +1,13 @@
+package style
+
+import "github.com/charmbracelet/lipgloss"
+
+// border maps strings to `lipgloss.Border`s
+var border map[string]lipgloss.Border = map[string]lipgloss.Border{
+	"double":  lipgloss.DoubleBorder(),
+	"hidden":  lipgloss.HiddenBorder(),
+	"none":    {},
+	"normal":  lipgloss.NormalBorder(),
+	"rounded": lipgloss.RoundedBorder(),
+	"thick":   lipgloss.ThickBorder(),
+}

style/command.go

@@ -0,0 +1,28 @@
+package style
+
+import (
+	"fmt"
+
+	"github.com/charmbracelet/lipgloss"
+)
+
+// Run provides a shell script interface for the Lip Gloss styling.
+// https://github.com/charmbracelet/lipgloss
+func (o Options) Run() {
+	fmt.Println(lipgloss.NewStyle().
+		Foreground(lipgloss.Color(o.Foreground)).
+		Background(lipgloss.Color(o.Background)).
+		BorderBackground(lipgloss.Color(o.BorderBackground)).
+		BorderForeground(lipgloss.Color(o.BorderForeground)).
+		Align(align[o.Align]).
+		Bold(o.Bold).
+		Border(border[o.Border]).
+		Margin(parseMargin(o.Margin)).
+		Padding(parsePadding(o.Padding)).
+		Height(o.Height).
+		Width(o.Width).
+		Faint(o.Faint).
+		Italic(o.Italic).
+		Strikethrough(o.Strikethrough).
+		Render(o.Text))
+}

style/options.go

@@ -0,0 +1,21 @@
+package style
+
+// Options is the customization options for the style command.
+type Options struct {
+	Text string `arg:"" optional:"" help:"Text to style"`
+
+	Background       string `help:"Background color"`
+	Foreground       string `help:"Foreground color"`
+	BorderBackground string `help:"Border background color"`
+	BorderForeground string `help:"Border foreground color"`
+	Align            string `help:"Text alignment" enum:"left,center,right,bottom,middle,top" default:"left"`
+	Border           string `help:"Border style to apply" enum:"none,hidden,normal,rounded,thick,double" default:"none"`
+	Height           int    `help:"Height of output"`
+	Width            int    `help:"Width of output"`
+	Margin           string `help:"Margin to apply around the text."`
+	Padding          string `help:"Padding to apply around the text."`
+	Bold             bool   `help:"Apply bold formatting"`
+	Faint            bool   `help:"Apply faint formatting"`
+	Italic           bool   `help:"Apply italic formatting"`
+	Strikethrough    bool   `help:"Apply strikethrough formatting"`
+}

style/spacing.go

@@ -0,0 +1,41 @@
+package style
+
+import (
+	"strconv"
+	"strings"
+)
+
+// parsePadding parses 1 - 4 integers from a string and returns them in a top,
+// right, bottom, left order for use in the lipgloss.Padding() method
+func parsePadding(s string) (int, int, int, int) {
+	var ints []int
+
+	tokens := strings.Split(s, " ")
+
+	// All tokens must be an integer
+	for _, token := range tokens {
+		parsed, err := strconv.Atoi(token)
+		if err != nil {
+			return 0, 0, 0, 0
+		}
+		ints = append(ints, parsed)
+	}
+
+	if len(tokens) == 1 {
+		return ints[0], ints[0], ints[0], ints[0]
+	}
+
+	if len(tokens) == 2 {
+		return ints[0], ints[1], ints[0], ints[1]
+	}
+
+	if len(tokens) == 4 {
+		return ints[0], ints[1], ints[2], ints[3]
+	}
+
+	return 0, 0, 0, 0
+}
+
+// parseMargin is an alias for parsePadding since they involve the same logic
+// to parse integers to the same format.
+var parseMargin = parsePadding

style/style.go

@@ -0,0 +1 @@
+package style