[bazel_migration][starnix] //src/starnix/modules/device_mapper

Migrate //src/starnix/modules/device_mapper from GN to Bazel.

The Starnix unit test packages are migrated too. Their Bazel test
components depend on //src/starnix/kernel/vdso directly (GN gets it
through //src/starnix/kernel/core's deps), bazel2gn generates the GN
copies, and the Bazel tests are not run in asan/hwasan builds, matching
the GN tests (https://fxbug.dev/42059075).

Test: fx test //src/starnix/modules/device_mapper:starnix-device-mapper-tests
Cq-Include-Trybots: luci.fuchsia.try:minimal.riscv64-release
Run-All-Tests: true
TAG: planter planter-20261026-56c4d848a70-local
Change-Id: I059caf1a3081f97a2fb801757d2413a58d57b7f7
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1911402
Presubmit-Verified: fuchsia-internal-scoped@luci-project-accounts.iam.gserviceaccount.com <fuchsia-internal-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jay Zhuang <jayzhuang@google.com>
Commit-Queue: Kevin Lindkvist <lindkvist@google.com>
Fuchsia-Auto-Submit: Kevin Lindkvist <lindkvist@google.com>