feat!: introduce color profiles and use term/ansi for styles

[aymanbagabas]

This introduces color profiles similar to Termenv color profiles. Plus, it switches to using Charmbracelet term & term/ansi to query terminal background color for the default renderer, and construct styles.

However, it breaks the renderer API since it doesn't depend on Termenv anymore.

func NewRenderer(cp Profile, hasDarkBackground bool) *Renderer

// New exported types
// Profile is a color profile: NoTTY, Ascii, ANSI, ANSI256, or TrueColor.
type Profile int

const (
	// NoTTY, not a terminal profile
	NoTTY Profile = iota
	// Ascii, uncolored profile
	Ascii // nolint: revive
	// ANSI, 4-bit color profile
	ANSI
	// ANSI256, 8-bit color profile
	ANSI256
	// TrueColor, 24-bit color profile
	TrueColor
)

// New exported funcs
func DetectColorProfile(stdout *os.File, environ []string) Profile
func EnvColorProfile(environ []string) Profile
func EnableLegacyWindowsANSI(out *os.File)

This also introduces a new color profile NoTTY. This profile doesn't generate any ANSI sequences, and, as the name suggests, is used when the renderer is dealing with a non-terminal output. The Ascii profile on the other hand is used to generate all the style sequences except color ones. This works well when NO_COLOR.

[bashbunni]

Nice! The latest changes fixed the Bubble Tea chat example for me. It's now using the right color profile instead of ascii. Tested all of the bubble tea examples last week and they all worked great even before the fix. Tested against the term/input branch of Bubble Tea btw