When `experimental.cacheComponents` is enabled, the static indicator in
the Next.js DevTools is now disabled.
With Cache Components enabled, the binary static/dynamic state is no
longer accurate since routes are typically partially static and dynamic
(unless fully opted into dynamic rendering via a Suspense boundary above
the body, which is an edge case).
To avoid confusion, we're removing it for now, when the feature flag is
enabled. In the future, we will likely provide better tools that will
allow users to understand which parts of a page are prerendered and
which parts are dynamic.
In addition, this PR also improves the behavior for fully static App
Router pages (without Cache Components). Previously, we would show
"Dynamic" as default, and only flipped to "Static" when the request was
finished. Now, we're showing a spinner while the page is loading.

closes NAR-428
### Why?
When users want to hide the dev indicator, they might be frustrated if
it reappears every reload. Hence, make a default to hide it for the
current server session or a day.
Closes NDX-890
---------
Co-authored-by: Zack Tanner <1939140+ztanner@users.noreply.github.com>
The static indicator was added in the new dev overlay but wasn't hooked up to pages router. This wires that up so they're properly marked static/dynamic.
Closes NDX-897
This PR removed the old overlay including the deprecated `buildActivity`
and `appIsrStatus` options.
Closes NDX-785
Closes NDX-855
Closes NDX-865
Closes NDX-866
Closes NDX-867
Closes NDX-868