Fix #6270: Allow change of color setting in TASTy Reflect

[nicolasstucki]

This provides a way to enabled and disable color when printing. The default is set to the current compiler setting.

Now, if someone wants a show that never prints the colors it can be implemented with

implicit def (expr: scala.quoted.Expr[T]) showColorless[T] (implicit reflect: Reflection): String = {
  import reflect._
  expr.unseal.showCode(the[Context].withoutColors)
}

Note that Tree.showCode will change name to Tree.show to match Expr.show.

[liufengyun]

Otherwise, LGTM

[liufengyun]

It's better to default to no colors other than ctx.printColors as that's what users want most of the time.

Otherwise, users will be forced to write x.show(the[Context].withColors) instead of x.show.

[liufengyun]

We can do either with a default color: Boolean = false or have two methods:

• show
• showColored

Both are more friendly than x.show(the[Context].withColors)

[nicolasstucki]

We cannot a default the is different for the compiler setting or every other use case will break.

As shown in the example it is easy to add your own version of show where you disregard the default settings.

[nicolasstucki]

We can always add some variant later

[liufengyun]

I think it's better to have it now as we go -- we will forget all these minor usability issues. If such usability issues accumulate, the user experience with Tasty Reflect will degrade.