https://linear.app/unleash/issue/2-582/display-the-change-request-created-with-variants-in-the-ui
Includes a basic diff visualisation on variants change requests.
It seems like components like `CodeSnippetPopover` and `PopoverDiff` are
currently very tightly coupled together with strategies, so I preferred
to follow my own approach and leave those alone for now instead of
trying to refactor them. `patchVariant` could also be renamed to a more
fitting name in the future as well, since we're now doing more of an
override than applying a patch.
`Diff` is a generic diff component that uses `EventDiff` internally and
simply takes into account a "before" and "after" state, as `preData` and
`data`.
I made some changes to `EventDiff` that made some sense to me:
- Cover edge cases where `path` is undefined and `.join` crashes, also
fallback to the diff index (or undefined);
- Leverage the key to correctly sort the change items in the diff;
