fixes #7363

Link - https://patternfly-pr-7497.surge.sh/components/table#expandable

To trigger the animation, in dev tools find a <tr class="pf-m-expanded pf-v6-c-table__expandable-row pf-v6-c-table__tr">, click on the ".cls" button in the top/right of dev tools (near the ":hov" hover/focus button) and toggle the .pf-m-expanded class. Here's a screenshot:

One note about this animation is, without some changes, on collapse the slide/fade runs and then the empty space collapses. I had mentioned that I expected the empty space to collapse immediately as the animation ran but I was mistaken - it collapses after the animation runs. WDYT @andrew-ronaldson @lboehling? I can update this and the other animations to collapse immediately if we prefer that interaction.

Currently table is different than some of the others because it uses display: none to hide the expandable content. As we discussed, we're OK with allowing transition-behavior: allow-discrete for that as a progressive enhancement (browser support here - https://caniuse.com/?search=allow-discrete). However, if we just go with that, then we'll also need to use @starting-style for the expand transition to work. @starting-style also doesn't have full browser support, either. Here's a TL;DR on where that stands with our official support. I'm only going to call out FF and Safari as they're the ones lagging with support for these two properties.

• PF supports FF and Safari v17.0+
• @starting-style only works on Safari starting v17.5. Works fine in FF.
• transition-behavior: allow-discrete only works on Safari starting v18, and doesn't work at all in FF.

So what does that mean?

• If you're on the latest browser of the ones we support, FF will only animate the "expand" state (due to support for @starting-style but no support for allow-discrete). Collapse animation will not work in FF.
• If you're on Safari v17.5+ (but not on v18), same as above - expansion animation works, collapse doesn't.
• If you're below Safari v17.5, you get no animation on expand or collapse.

I mention this because I believe I overheard that we would use allow-discrete and for anyone that uses a browser that doesn't support it, they would get the expand animation but not the collapse animation, and I wanted to call out that if you're below Safari v17.5, you won't get either.

If that's OK then 🚀. If not, we can work around it, we'll probably just need to add a new class or two and react will need an update, too.