* MM-62710 Ensure CommentedOn message is never missing due to unloaded data
There's more information in the Jira ticket on how this occurs, but the
short version is that there's a way for either the root post and/or the
root post's author to be missing which previously caused the "Commented
On" line not to be rendered for a comment with CRT disabled. That caused
the post to appear as if it was part of the wrong thread.
Now, the CommentedOn component is always mounted when for the first
non-consecutive reply to a thread, and it knows how to load that missing
data itself.
I also took the opportunity to implement basic `useUser` and `usePost`
hooks which will fetch the user/post if needed. They're both implemented
using a shared `makeUseEntity` which should be usable for other entities
(objects stored in Redux state and fetched using a Redux action). These
also both use actions that use `DelayedDataLoader` to batch and debounce
requests for that data as well!
Assuming this works well, I'm hoping we can start using this pattern
elsewhere in the app.
* Update tests and remove unneeded mapStateToProps
* Address feedback
* Fix playwright tests
* revert Fix playwright tests
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Co-authored-by: yasserfaraazkhan <attitude3cena.yf@gmail.com>
d25326764f