Previously, we had the same logic in a couple of places to safely access
the `Window`'s `local-/sessionStorage` and provide a no-op fallback if
necessary. Soon, we will need the same logic for the cookies popup
(see #42209).
This commit reduces code duplication by providing
`local-/sessionStorage` as injectables and sharing the logic for
accessing them safely. This also makes it easier to mock the storage in
tests without having to mess with the actual `Window` object.
NOTE:
This commit actually decreases the payload size in the `main` bundle by
40B.
PR Close#42259