[roll] Roll fuchsia [bazel_migration] Make botanist binary Bazel-only

Botanist libraries are still used by other GN Go targets, so they need
to be synced with bazel2gn.

NOTE: botanist failed to cross-compile for arm64 hosts because botanist,
and many of its transitive dependencies under //tools and //src,
strictly limited their `target_compatible_with` to `HOST_CONSTRAINTS`
(which limits both OS and CPU architecture). It needs to be
cross-compiled because it needs to run on arm64 hosts, see [0]. This
change updated all of botanist's recursive dependencies to use
`HOST_OS_CONSTRAINTS`, so it can be cross-compiled.

Updated `public` visibility to `//:__subpackages` in changed BUILD.bazel
files when I'm at it.

[0] https://cs.opensource.google/fuchsia/fuchsia/+/main:bundles/infra/test/BUILD.gn;l=57;drc=ade667fae1d358ec2daf0cb25008943f850dc587

TAG=agy
CONV=08aed152-6cd6-4955-9c69-ecb0eb50fc2d

Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1813690
Original-Original-Revision: a16de80df0de4797fa00a74e9eaaae2a1bc8e72f
GitOrigin-RevId: bdaaf08ef94818b5cff0c6fede80cfd11e123ea5
Change-Id: If98364dd75322840e98b765a3c86edf114956f7f
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1818332
Cr-Commit-Position: refs/heads/main@{#201807}