dillon1000/react

Add compareDocumentPosition to fragment instances (#32722)

This adds `compareDocumentPosition(otherNode)` to fragment instances.

The semantics implemented are meant to match typical element
positioning, with some fragment specifics. See the unit tests for all
expectations.

- An element preceding a fragment is `Node.DOCUMENT_POSITION_PRECEDING`
- An element after a fragment is `Node.DOCUMENT_POSITION_FOLLOWING`
- An element containing the fragment is
`Node.DOCUMENT_POSITION_PRECEDING` and
`Node.DOCUMENT_POSITION_CONTAINING`
- An element within the fragment is
`Node.DOCUMENT_POSITION_CONTAINED_BY`
- An element compared against an empty fragment will result in
`Node.DOCUMENT_POSITION_DISCONNECTED` and
`Node.DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC`

Since we assume a fragment instances target children are DOM siblings
and we want to compare the full fragment as a pseudo container, we can
compare against the first target child outside of handling the special
cases (empty fragments and contained elements).