Seed CacheNodes immediately after receiving response (#58669)
## Based on #58666
*I submitted this stack as separate PRs so I could run CI but I want to
land them as a single unit. So I've left all but this last one in draft
mode. You can review them commit-by-commit.*
We render nested layouts in parallel on the server. This means we should
be able to create a CacheNode entry for every layout in the tree as soon
as the Flight response is received by the client, even before the nested
layouts have streamed in. Currently, we wait until the nested layouts
start rendering before we write them into the cache, which prevents us
from performing certain optimizations. That's because the CacheNodes are
sent as a prop to LayoutRouter; the only way to unwrap the CacheNode is
to wait for LayoutRouter to render.
In previous PRs, I updated the server to create a top-level data
structure that contains all the CacheNodes for the entire tree. This PR
updates the client side to receive the nodes and write them into the
cache.
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Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
