[roll] Roll fuchsia [revert] Revert "[pkg-cache][pkgfs][fshost] pkg-cache provides all pkgfs directories"

This reverts commit 021b6cdc9d9e0bd5f91f5a083fec30e7dfd1791f.

Reason for revert: Broke file access on some OOT clients.

Original change's description:
> [pkg-cache][pkgfs][fshost] pkg-cache provides all pkgfs directories
>
> All pkgfs directories (including pkgfs/, pkgfs/packages/,
> pkgfs/versions/, and pkgfs/system/) are now provided by pkg-cache
> instead of pkgfs.
>
> Package directories themselves (including the elements of
> pkgfs/versions/ and pkgfs/packages/*/*/ and the /pkg directory mounted
> in components' namespaces) are now served by pkg-cache instead of
> pkgfs.
>
> The pkgfs directories and package directories themselves are
> implemented on top of the Rust VFS library. As a result, they now
> enforce hierarchical rights (e.g. opening a file with RIGHT_READABLE
> requires that the directory connection over which the
> fuchsia.io/Directory.Open FIDL call was made had RIGHT_READABLE) and
> perform more validation of the flag, mode, and path
> arguments (e.g. paths of the empty string and paths containing ".."
> segments are now rejected). See
> https://cs.opensource.google/fuchsia/fuchsia/+/main:src/sys/pkg/tests/pkgdir/README.md
> for a full listing of the package directory behavior changes.
>
> fshost no longer starts pkgfs (sometimes called pkgsvr).
>
> pkg-cache is now routed an executable handle to blobfs (so it can serve
> package directories).
>
> pkg-cache is now a child of bootstrap and is resolved by the
> base-resolver.
>
> pkg-cache's other package APIs (fuchsia.pkg/PackageCache.{Open|Get}) now
> use the same machinery that powers its pkgfs replacements (instead of
> forwarding to pkgfs).
>
> Original-Bug: 99148
> Original-Fixed: 88871
> Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/630466

Original-Bug: 99148
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/678298
Original-Revision: 631fa7a0a06c38fa7e58d8398554f45ca70ea36b
GitOrigin-RevId: c07f8d6dc6eb105be82c0ed9ad3796a794746a4b
Change-Id: Ieb1fc35d46a4f44470326eb668143ae96c8c9dd4