feat: join borders layout functions

[pachecot]

Added functions JoinBorderVertical & JoinBorderHorizontal based on JoinVertical & JoinHorizontal. Adds an additional style argument for border information. Draws joining borders as the blocks are joined.

	s := lipgloss.NewStyle().
		Border(lipgloss.NormalBorder()).
		BorderForeground(lipgloss.Color("#FF0000"))

	fmt.Println()
	fmt.Println(lipgloss.JoinBorderHorizontal(s, 0, "Alpha", "Bravo", "Charlie", "Delta"))
	fmt.Println()
	fmt.Println(lipgloss.JoinBorderVertical(s, 0, "Alpha", "Bravo", "Charlie", "Delta"))
	fmt.Println()