Enable experimental.cachedNavigations by default with cacheComponents (#94012)
Turns on `experimental.cachedNavigations` by default for projects
already on `cacheComponents`. Last of the Sparkle stack.
Tied to `cacheComponents` rather than flipped unconditionally because
`cachedNavigations` is a no-op without it, and the existing validation
already throws if you set it without `cacheComponents` — so an
unconditional flip would break every non-Cache-Components project.
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