Require less props for basic Transition usages

[stramel]

I think there is an opportunity to simplify the required props on Transition.

A lot of usages that I have done and seen for Transition are pretty basic and can be inverted. For example:

<Transition.Child
    enter="transition duration-300 ease-in-out transform"
    enterFrom="-translate-x-full"
    enterTo="translate-x-0"
    leave="transition duration-300 ease-in-out transform"
    leaveFrom="translate-x-0"
    leaveTo="-translate-x-full"
 >

I think we could allow leaveFrom and leaveTo be the reverse of enterFrom and enterTo by default. I know I could deduplicate some of the classes from the transition into the className prop, but I like having the transition specific classes separated out from other classes that I'm applying in there. It would be nice if leave defaulted to enter's classes.

So it would result in something like:

<Transition.Child
    enter="transition duration-300 ease-in-out transform"
    enterFrom="-translate-x-full"
    enterTo="translate-x-0"
 >

This still leaves room for customizing the leave transition but makes it simpler to use for basic use-cases.

Another example, with my custom className:

<Transition.Child
   className="fixed inset-0"
   enter="transition-opacity ease-linear duration-300"
   enterFrom="opacity-0"
   enterTo="opacity-100"
   leave="transition-opacity ease-linear duration-300"
   leaveFrom="opacity-100"
   leaveTo="opacity-0"
>

could just be

<Transition.Child
   className="fixed inset-0"
   enter="transition-opacity ease-linear duration-300"
   enterFrom="opacity-0"
   enterTo="opacity-100"
>